From fbeef1538c5310c815bed8802311406bfef4d0d3 Mon Sep 17 00:00:00 2001
From: Dimitri POSTOLOV <dmytropostolov@gmail.com>
Date: Fri, 29 Nov 2024 14:21:47 +0700
Subject: [PATCH] [v4] setup `@typescript-eslint/no-unnecessary-condition` rule
 and fix warnings (#3747)

* more

* more

* more

* more

* more

* more

* more

* more

* more

* more

* more

* more

* more

* more

* more

* more

* more

* more

* more

* fix

* aa

* more

* more

* more

* fix typecheck
---
 .changeset/blue-crabs-deny.md                 |  7 +++
 docs/app/docs/built-ins/head/_slider.tsx      |  2 +-
 docs/app/og/route.tsx                         |  2 +-
 docs/tsconfig.json                            |  3 +-
 examples/blog/app/posts/get-posts.js          |  3 +-
 examples/blog/app/posts/page.jsx              |  6 ++-
 examples/blog/app/tags/[tag]/page.jsx         |  6 ++-
 .../app/_dictionaries/get-dictionary.ts       | 11 +----
 examples/swr-site/tsconfig.json               |  3 +-
 .../src/index.ts                              |  1 +
 .../tsconfig.json                             |  3 +-
 packages/eslint-config/src/index.ts           | 32 ++++++------
 packages/eslint-config/tsconfig.json          |  2 +-
 .../nextra-theme-blog/src/components/meta.tsx |  9 ++--
 .../nextra-theme-blog/src/mdx-components.tsx  |  7 ++-
 packages/nextra-theme-blog/tsconfig.json      |  3 +-
 .../src/components/locale-switch.tsx          |  4 +-
 .../src/components/navbar/index.client.tsx    |  1 +
 .../src/components/sidebar.tsx                | 49 ++++++++++---------
 .../src/mdx-components/wrapper.client.tsx     |  3 +-
 packages/nextra-theme-docs/tsconfig.json      |  3 +-
 packages/nextra/loader.cjs                    |  2 +-
 .../nextra/src/client/components/head.tsx     |  8 +--
 .../client/components/popup/index.client.tsx  |  1 +
 .../nextra/src/client/components/search.tsx   |  7 +--
 .../src/client/hocs/with-github-alert.tsx     |  6 ++-
 .../mdx-components/pre/copy-to-clipboard.tsx  |  4 --
 packages/nextra/src/client/normalize-pages.ts |  9 ++--
 packages/nextra/src/env.d.ts                  | 20 ++++----
 .../folder-without-markdown-files/test.ts     |  1 +
 .../nextra/src/server/__tests__/latex.test.ts |  2 +-
 .../src/server/__tests__/normalize.test.ts    |  6 +--
 .../nextra/src/server/compile-metadata.ts     |  2 +-
 packages/nextra/src/server/compile.ts         |  8 +--
 .../src/server/fetch-filepaths-from-github.ts |  1 +
 packages/nextra/src/server/index.ts           | 10 ++--
 packages/nextra/src/server/loader.ts          |  2 +-
 packages/nextra/src/server/locales.ts         |  2 +-
 .../page-map/merge-meta-with-page-map.ts      |  2 +-
 .../nextra/src/server/page-map/normalize.ts   | 34 ++++++-------
 .../nextra/src/server/page-map/placeholder.ts |  1 +
 .../nextra/src/server/page-map/to-page-map.ts |  3 ++
 .../src/server/recma-plugins/recma-rewrite.ts |  4 +-
 .../rehype-better-react-mathjax.ts            |  7 +--
 .../rehype-extract-toc-content.ts             |  2 +-
 .../src/server/rehype-plugins/rehype.ts       |  4 +-
 .../server/remark-plugins/remark-mdx-title.ts |  2 +-
 packages/nextra/src/server/twoslash.ts        |  8 +--
 packages/nextra/tsconfig.json                 |  3 +-
 packages/nextra/tsup.config.ts                |  2 +-
 50 files changed, 181 insertions(+), 142 deletions(-)
 create mode 100644 .changeset/blue-crabs-deny.md

diff --git a/.changeset/blue-crabs-deny.md b/.changeset/blue-crabs-deny.md
new file mode 100644
index 0000000000..dd79c8bc16
--- /dev/null
+++ b/.changeset/blue-crabs-deny.md
@@ -0,0 +1,7 @@
+---
+"nextra-theme-blog": patch
+"nextra-theme-docs": patch
+"nextra": patch
+---
+
+setup `@typescript-eslint/no-unnecessary-condition` rule and fix warnings
diff --git a/docs/app/docs/built-ins/head/_slider.tsx b/docs/app/docs/built-ins/head/_slider.tsx
index 271cdf9625..f2fad2811a 100644
--- a/docs/app/docs/built-ins/head/_slider.tsx
+++ b/docs/app/docs/built-ins/head/_slider.tsx
@@ -36,7 +36,7 @@ export const Slider: FC = ({
 }
 
 function hexToRgb(hex: `#${string}`): string {
-  const bigint = parseInt(hex.slice(1), 16)
+  const bigint = Number.parseInt(hex.slice(1), 16)
   const r = (bigint >> 16) & 255
   const g = (bigint >> 8) & 255
   const b = bigint & 255
diff --git a/docs/app/og/route.tsx b/docs/app/og/route.tsx
index 37a818cc13..04795d22f5 100644
--- a/docs/app/og/route.tsx
+++ b/docs/app/og/route.tsx
@@ -4,7 +4,7 @@ import { ImageResponse } from 'next/og'
 
 export const runtime = 'edge'
 
-const font = fetch(new URL('./Inter-SemiBold.otf', import.meta.url)).then(res =>
+const font = fetch(new URL('Inter-SemiBold.otf', import.meta.url)).then(res =>
   res.arrayBuffer()
 )
 
diff --git a/docs/tsconfig.json b/docs/tsconfig.json
index e0c194d17a..312a3448e2 100644
--- a/docs/tsconfig.json
+++ b/docs/tsconfig.json
@@ -23,7 +23,8 @@
         "name": "next"
       }
     ],
-    "strictNullChecks": true
+    "strictNullChecks": true,
+    "noUncheckedIndexedAccess": true
   },
   "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx", ".next/types/**/*.ts"],
   "exclude": ["node_modules", ".next"]
diff --git a/examples/blog/app/posts/get-posts.js b/examples/blog/app/posts/get-posts.js
index f5bd0d4252..f33e6f37cb 100644
--- a/examples/blog/app/posts/get-posts.js
+++ b/examples/blog/app/posts/get-posts.js
@@ -12,6 +12,7 @@ export async function getPosts() {
 }
 
 export async function getTags() {
-  const tags = (await getPosts()).flatMap(post => post.frontMatter.tags)
+  const posts = await getPosts()
+  const tags = posts.flatMap(post => post.frontMatter.tags)
   return tags
 }
diff --git a/examples/blog/app/posts/page.jsx b/examples/blog/app/posts/page.jsx
index 054e9d8dd2..47b3d2c970 100644
--- a/examples/blog/app/posts/page.jsx
+++ b/examples/blog/app/posts/page.jsx
@@ -7,7 +7,9 @@ export const metadata = {
 }
 
 export default async function PostsPage() {
-  const allTags = (await getTags()).reduce((acc, curr) => {
+  const tags = await getTags()
+  const posts = await getPosts()
+  const allTags = tags.reduce((acc, curr) => {
     acc[curr] ??= 0
     acc[curr] += 1
     return acc
@@ -26,7 +28,7 @@ export default async function PostsPage() {
           </Link>
         ))}
       </div>
-      {(await getPosts()).map(post => (
+      {posts.map(post => (
         <PostCard key={post.route} post={post} />
       ))}
     </div>
diff --git a/examples/blog/app/tags/[tag]/page.jsx b/examples/blog/app/tags/[tag]/page.jsx
index 39eb22f0e2..fce9f1eb84 100644
--- a/examples/blog/app/tags/[tag]/page.jsx
+++ b/examples/blog/app/tags/[tag]/page.jsx
@@ -15,10 +15,12 @@ export async function generateStaticParams() {
 
 export default async function TagPage(props) {
   const params = await props.params
+  const { title } = await generateMetadata({ params })
+  const posts = await getPosts()
   return (
     <>
-      <h1>{(await generateMetadata({ params })).title}</h1>
-      {(await getPosts())
+      <h1>{title}</h1>
+      {posts
         .filter(post =>
           post.frontMatter.tags.includes(decodeURIComponent(params.tag))
         )
diff --git a/examples/swr-site/app/_dictionaries/get-dictionary.ts b/examples/swr-site/app/_dictionaries/get-dictionary.ts
index 7e5a08cd3f..86c4b83859 100644
--- a/examples/swr-site/app/_dictionaries/get-dictionary.ts
+++ b/examples/swr-site/app/_dictionaries/get-dictionary.ts
@@ -9,7 +9,7 @@ const dictionaries: Dictionaries = {
   ru: () => import('./ru')
 }
 
-export async function getDictionary(locale: Locale): Promise<Dictionary> {
+export async function getDictionary(locale: string): Promise<Dictionary> {
   const { default: dictionary } = await (
     dictionaries[locale] || dictionaries.en
   )()
@@ -18,12 +18,5 @@ export async function getDictionary(locale: Locale): Promise<Dictionary> {
 }
 
 export function getDirection(locale: Locale): 'ltr' | 'rtl' {
-  switch (locale) {
-    case 'es':
-      return 'rtl'
-    case 'en':
-    case 'ru':
-    default:
-      return 'ltr'
-  }
+  return locale === 'es' ? 'rtl' : 'ltr'
 }
diff --git a/examples/swr-site/tsconfig.json b/examples/swr-site/tsconfig.json
index c34283ef38..b17c6c3395 100644
--- a/examples/swr-site/tsconfig.json
+++ b/examples/swr-site/tsconfig.json
@@ -23,7 +23,8 @@
         "name": "next"
       }
     ],
-    "strictNullChecks": true
+    "strictNullChecks": true,
+    "noUncheckedIndexedAccess": true
   },
   "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx", ".next/types/**/*.ts"],
   "exclude": ["node_modules", ".next"]
diff --git a/packages/esbuild-react-compiler-plugin/src/index.ts b/packages/esbuild-react-compiler-plugin/src/index.ts
index f0349fa787..f62dde6c07 100644
--- a/packages/esbuild-react-compiler-plugin/src/index.ts
+++ b/packages/esbuild-react-compiler-plugin/src/index.ts
@@ -45,6 +45,7 @@ export const reactCompilerPlugin = (
               relativePath,
               'was not optimized with react-compiler'
             )
+            console.log(result)
           }
 
           resolve({ contents: result, loader })
diff --git a/packages/esbuild-react-compiler-plugin/tsconfig.json b/packages/esbuild-react-compiler-plugin/tsconfig.json
index 61aa255661..601682dd6e 100644
--- a/packages/esbuild-react-compiler-plugin/tsconfig.json
+++ b/packages/esbuild-react-compiler-plugin/tsconfig.json
@@ -10,7 +10,8 @@
     "strictNullChecks": true,
     "lib": ["esnext", "dom"],
     "moduleResolution": "node",
-    "resolveJsonModule": true
+    "resolveJsonModule": true,
+    "noUncheckedIndexedAccess": true
   },
   "exclude": ["dist"]
 }
diff --git a/packages/eslint-config/src/index.ts b/packages/eslint-config/src/index.ts
index 34dd68d9a1..046f34ab44 100644
--- a/packages/eslint-config/src/index.ts
+++ b/packages/eslint-config/src/index.ts
@@ -46,11 +46,11 @@ const config: Config = tseslint.config(
     extends: [
       js.configs.recommended,
       tseslint.configs.recommended,
+      eslintPluginUnicorn.configs['flat/recommended'],
       eslintConfigPrettier
     ],
     plugins: {
       import: eslintPluginImport,
-      unicorn: eslintPluginUnicorn,
       sonarjs: eslintPluginSonarJs
     },
     rules: {
@@ -68,13 +68,8 @@ const config: Config = tseslint.config(
         { VariableDeclarator: { object: true } }
       ],
       'import/no-duplicates': 'error',
-      'no-negated-condition': 'off',
-      'unicorn/no-negated-condition': 'error',
       'prefer-regex-literals': ['error', { disallowRedundantWrapping: true }],
       'object-shorthand': ['error', 'always'],
-      'unicorn/prefer-regexp-test': 'error',
-      'unicorn/no-array-for-each': 'error',
-      'unicorn/prefer-string-replace-all': 'error',
       '@typescript-eslint/prefer-for-of': 'error',
       quotes: ['error', 'single', { avoidEscape: true }], // Matches Prettier, but also replaces backticks
       '@typescript-eslint/no-unused-vars': [
@@ -86,21 +81,29 @@ const config: Config = tseslint.config(
       ],
       'prefer-object-spread': 'error',
       'prefer-arrow-callback': ['error', { allowNamedFunctions: true }],
-      'unicorn/prefer-at': 'error',
       'sonarjs/no-small-switch': 'error',
       'prefer-const': ['error', { destructuring: 'all' }],
-      'unicorn/prefer-array-index-of': 'error',
       'sonarjs/no-unused-collection': 'error',
-      'unicorn/catch-error-name': 'error',
-      'unicorn/prefer-optional-catch-binding': 'error',
-      'unicorn/filename-case': 'error',
       eqeqeq: ['error', 'always', { null: 'ignore' }],
-      'unicorn/prefer-node-protocol': 'error',
+      'unicorn/switch-case-braces': ['error', 'avoid'],
       // todo: enable
       '@typescript-eslint/no-explicit-any': 'off',
       '@typescript-eslint/no-non-null-assertion': 'off',
       '@typescript-eslint/no-var-requires': 'off',
-      '@typescript-eslint/ban-ts-comment': 'off'
+      '@typescript-eslint/ban-ts-comment': 'off',
+
+      'unicorn/no-hex-escape': 'off', // todo
+      'unicorn/escape-case': 'off', // todo
+      'unicorn/consistent-function-scoping': 'off', // todo
+      'unicorn/prefer-module': 'off',
+      'unicorn/no-array-reduce': 'off',
+      'unicorn/prefer-top-level-await': 'off', // Check if possible to refactor without breaking
+
+      'unicorn/prevent-abbreviations': 'off', // Too many cases
+      'unicorn/explicit-length-check': 'off', // I don't like
+      'unicorn/no-null': 'off', // I don't like
+      'unicorn/prefer-global-this': 'off', // Bundlers are smarter with window
+      'unicorn/prefer-optional-catch-binding': 'off' // catch by @typescript-eslint/no-unused-vars
     }
   },
   // Rules for React files
@@ -174,7 +177,8 @@ const config: Config = tseslint.config(
       '@typescript-eslint/prefer-destructuring': [
         'error',
         { VariableDeclarator: { object: true } }
-      ]
+      ],
+      '@typescript-eslint/no-unnecessary-condition': 'error'
     }
   },
   {
diff --git a/packages/eslint-config/tsconfig.json b/packages/eslint-config/tsconfig.json
index 61aa255661..7748061561 100644
--- a/packages/eslint-config/tsconfig.json
+++ b/packages/eslint-config/tsconfig.json
@@ -10,7 +10,7 @@
     "strictNullChecks": true,
     "lib": ["esnext", "dom"],
     "moduleResolution": "node",
-    "resolveJsonModule": true
+    "noUncheckedIndexedAccess": true
   },
   "exclude": ["dist"]
 }
diff --git a/packages/nextra-theme-blog/src/components/meta.tsx b/packages/nextra-theme-blog/src/components/meta.tsx
index a13584b098..da32fe6a38 100644
--- a/packages/nextra-theme-blog/src/components/meta.tsx
+++ b/packages/nextra-theme-blog/src/components/meta.tsx
@@ -32,9 +32,12 @@ export const Meta: FC<BlogMetadata & { children: ReactNode }> = ({
 
           {children}
 
-          {(author || date) && (readingTime || tags?.length) && (
-            <span className="x:px-1">•</span>
-          )}
+          {
+            // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition -- fixme
+            (author || date) && (readingTime || tags?.length) && (
+              <span className="x:px-1">•</span>
+            )
+          }
           {readingTimeText || tagsEl}
         </div>
         {readingTime && (
diff --git a/packages/nextra-theme-blog/src/mdx-components.tsx b/packages/nextra-theme-blog/src/mdx-components.tsx
index 2ae082f9b4..ab17bcf027 100644
--- a/packages/nextra-theme-blog/src/mdx-components.tsx
+++ b/packages/nextra-theme-blog/src/mdx-components.tsx
@@ -98,8 +98,11 @@ export const useMDXComponents = ({
           <Meta {...(metadata as BlogMetadata)}>
             {dateObj && (
               <time dateTime={dateObj.toISOString()}>
-                {(DateFormatter && <DateFormatter date={dateObj} />) ||
-                  dateObj.toLocaleDateString()}
+                {DateFormatter ? (
+                  <DateFormatter date={dateObj} />
+                ) : (
+                  dateObj.toLocaleDateString()
+                )}
               </time>
             )}
           </Meta>
diff --git a/packages/nextra-theme-blog/tsconfig.json b/packages/nextra-theme-blog/tsconfig.json
index 669156281f..a6413b99ac 100644
--- a/packages/nextra-theme-blog/tsconfig.json
+++ b/packages/nextra-theme-blog/tsconfig.json
@@ -10,7 +10,8 @@
     "strictNullChecks": true,
     "jsx": "react-jsx",
     "moduleResolution": "bundler",
-    "types": ["vitest/globals"]
+    "types": ["vitest/globals"],
+    "noUncheckedIndexedAccess": true
   },
   "exclude": ["dist"]
 }
diff --git a/packages/nextra-theme-docs/src/components/locale-switch.tsx b/packages/nextra-theme-docs/src/components/locale-switch.tsx
index b39a98e4e3..88bc819a61 100644
--- a/packages/nextra-theme-docs/src/components/locale-switch.tsx
+++ b/packages/nextra-theme-docs/src/components/locale-switch.tsx
@@ -7,7 +7,7 @@ import { GlobeIcon } from 'nextra/icons'
 import type { FC } from 'react'
 import { useThemeConfig } from '../stores'
 
-const ONE_YEAR = 365 * 24 * 60 * 60 * 1_000
+const ONE_YEAR = 365 * 24 * 60 * 60 * 1000
 
 interface LocaleSwitchProps {
   lite?: boolean
@@ -29,7 +29,7 @@ export const LocaleSwitch: FC<LocaleSwitchProps> = ({ lite, className }) => {
         document.cookie = `NEXT_LOCALE=${lang}; expires=${date.toUTCString()}; path=/`
         location.href = addBasePath(pathname.replace(`/${locale}`, `/${lang}`))
       }}
-      value={locale}
+      value={locale!}
       selectedOption={
         <span className="x:flex x:items-center x:gap-2">
           <GlobeIcon height="12" />
diff --git a/packages/nextra-theme-docs/src/components/navbar/index.client.tsx b/packages/nextra-theme-docs/src/components/navbar/index.client.tsx
index d981a76195..764dd324ae 100644
--- a/packages/nextra-theme-docs/src/components/navbar/index.client.tsx
+++ b/packages/nextra-theme-docs/src/components/navbar/index.client.tsx
@@ -66,6 +66,7 @@ const NavbarMenu: FC<{
         anchor={{ to: 'top end', gap: 10, padding: 16 }}
       >
         {Object.entries(
+          // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition -- fixme
           (menu.items as Record<string, { title: string; href?: string }>) || {}
         ).map(([key, item]) => (
           <_MenuItem
diff --git a/packages/nextra-theme-docs/src/components/sidebar.tsx b/packages/nextra-theme-docs/src/components/sidebar.tsx
index a88500c29e..9e325d9c85 100644
--- a/packages/nextra-theme-docs/src/components/sidebar.tsx
+++ b/packages/nextra-theme-docs/src/components/sidebar.tsx
@@ -75,7 +75,7 @@ type FolderProps = {
 
 const Folder: FC<FolderProps> = ({ item, anchors, onFocus, level }) => {
   const routeOriginal = useFSRoute()
-  const [route] = routeOriginal.split('#', 1)
+  const route = routeOriginal.split('#', 1)[0]!
   const hasRoute = !!item.route // for item.type === 'menu' will be ''
   const active = hasRoute && [route, route + '/'].includes(item.route + '/')
   const activeRouteInside =
@@ -99,19 +99,20 @@ const Folder: FC<FolderProps> = ({ item, anchors, onFocus, level }) => {
 
   const [, rerender] = useState<object>()
 
-  const handleClick: MouseEventHandler = useCallback(event => {
-    const el = event.currentTarget
-    const isClickOnIcon =
-      el /* will be always <a> or <button> */ !==
-      event.target /* can be <svg> or <path> */
-    if (isClickOnIcon) {
-      event.preventDefault()
-    }
-    const isOpen = el.parentElement!.classList.contains('open')
-    const route = el.getAttribute('href') || el.getAttribute('data-href') || ''
-    TreeState[route] = !isOpen
-    rerender({})
-  }, [])
+  const handleClick: MouseEventHandler<HTMLAnchorElement | HTMLButtonElement> =
+    useCallback(event => {
+      const el = event.currentTarget
+      const isClickOnIcon =
+        el /* will be always <a> or <button> */ !==
+        event.target /* can be <svg> or <path> */
+      if (isClickOnIcon) {
+        event.preventDefault()
+      }
+      const isOpen = el.parentElement!.classList.contains('open')
+      const route = el.getAttribute('href') || el.dataset.href || ''
+      TreeState[route] = !isOpen
+      rerender({})
+    }, [])
 
   useEffect(() => {
     function updateTreeState() {
@@ -140,12 +141,14 @@ const Folder: FC<FolderProps> = ({ item, anchors, onFocus, level }) => {
     const routes = Object.fromEntries(
       (menu.children || []).map(route => [route.name, route])
     )
-    item.children = Object.entries(menu.items || {}).map(([key, item]) => {
-      return {
-        ...(routes[key] || { name: key /* for React key prop */ }),
-        ...(item as object)
-      }
-    })
+    // @ts-expect-error
+    item.children = Object.entries(menu.items || {}) // eslint-disable-line @typescript-eslint/no-unnecessary-condition -- fixme
+      .map(([key, item]) => {
+        return {
+          ...(routes[key] || { name: key /* for React key prop */ }),
+          ...(item as object)
+        }
+      })
   }
 
   const isLink = 'frontMatter' in item
@@ -265,11 +268,9 @@ interface MenuProps {
   level: number
 }
 
-const handleFocus: FocusEventHandler = event => {
+const handleFocus: FocusEventHandler<HTMLAnchorElement> = event => {
   const route =
-    event.target.getAttribute('href') ||
-    event.target.getAttribute('data-href') ||
-    ''
+    event.target.getAttribute('href') || event.target.dataset.href || ''
   setFocusedRoute(route)
 }
 
diff --git a/packages/nextra-theme-docs/src/mdx-components/wrapper.client.tsx b/packages/nextra-theme-docs/src/mdx-components/wrapper.client.tsx
index 924b4234e3..360060a4dc 100644
--- a/packages/nextra-theme-docs/src/mdx-components/wrapper.client.tsx
+++ b/packages/nextra-theme-docs/src/mdx-components/wrapper.client.tsx
@@ -14,8 +14,7 @@ export const ClientWrapper: MDXWrapper = ({ toc, children, metadata }) => {
   } = useConfig().normalizePagesResult
   const themeConfig = useThemeConfig()
 
-  const date =
-    themeContext.timestamp && themeConfig.lastUpdated && metadata.timestamp
+  const date = themeContext.timestamp && metadata.timestamp
 
   // We can't update store in server component so doing it in client component
   useEffect(() => {
diff --git a/packages/nextra-theme-docs/tsconfig.json b/packages/nextra-theme-docs/tsconfig.json
index 81499efef4..5b751b2874 100644
--- a/packages/nextra-theme-docs/tsconfig.json
+++ b/packages/nextra-theme-docs/tsconfig.json
@@ -11,7 +11,8 @@
     "jsx": "react-jsx",
     "moduleResolution": "bundler",
     "lib": ["ESNext", "DOM"],
-    "types": ["vitest/globals"]
+    "types": ["vitest/globals"],
+    "noUncheckedIndexedAccess": true
   },
   "exclude": ["dist"]
 }
diff --git a/packages/nextra/loader.cjs b/packages/nextra/loader.cjs
index a5a9f92c1d..64987cdc5f 100755
--- a/packages/nextra/loader.cjs
+++ b/packages/nextra/loader.cjs
@@ -10,7 +10,7 @@
  * @param {string} code
  * @return {Promise<void>}
  */
-module.exports = async function (code) {
+module.exports = async function loader(code) {
   const callback = this.async()
 
   try {
diff --git a/packages/nextra/src/client/components/head.tsx b/packages/nextra/src/client/components/head.tsx
index 112133fd8e..80474f909c 100644
--- a/packages/nextra/src/client/components/head.tsx
+++ b/packages/nextra/src/client/components/head.tsx
@@ -13,7 +13,7 @@ const darkLightSchema = z
   .transform(v => (typeof v === 'number' ? { dark: v, light: v } : v))
 
 function hexToRgb(hex: `#${string}`): string {
-  const bigint = parseInt(hex.slice(1), 16)
+  const bigint = Number.parseInt(hex.slice(1), 16)
   const r = (bigint >> 16) & 255
   const g = (bigint >> 8) & 255
   const b = bigint & 255
@@ -30,9 +30,9 @@ const colorSchema = z
     if (value.startsWith('#')) {
       return hexToRgb(value as `#${string}`)
     }
-    const groups = value.match(/^rgb\((?<rgb>.*?)\)$/)?.groups
-    if (groups) {
-      return groups.rgb.replaceAll(' ', '')
+    const rgb = value.match(/^rgb\((?<rgb>.*?)\)$/)?.groups!.rgb
+    if (rgb) {
+      return rgb.replaceAll(' ', '')
     }
     return value
   })
diff --git a/packages/nextra/src/client/components/popup/index.client.tsx b/packages/nextra/src/client/components/popup/index.client.tsx
index 195a305c60..6d10806b1f 100644
--- a/packages/nextra/src/client/components/popup/index.client.tsx
+++ b/packages/nextra/src/client/components/popup/index.client.tsx
@@ -11,6 +11,7 @@ const PopupContext = createContext<boolean | null>(null)
 function usePopup(): boolean {
   const ctx = useContext(PopupContext)
   if (typeof ctx !== 'boolean') {
+    // eslint-disable-next-line unicorn/prefer-type-error -- Doesn't fit in this case
     throw new Error('`usePopup` must be used within a `<Popup>` component')
   }
   return ctx
diff --git a/packages/nextra/src/client/components/search.tsx b/packages/nextra/src/client/components/search.tsx
index 82a2de0bce..64c6318ea8 100644
--- a/packages/nextra/src/client/components/search.tsx
+++ b/packages/nextra/src/client/components/search.tsx
@@ -20,7 +20,7 @@ export async function importPagefind() {
   window.pagefind = await import(
     /* webpackIgnore: true */ addBasePath('/_pagefind/pagefind.js')
   )
-  await window.pagefind.options({
+  await window.pagefind!.options({
     baseUrl: '/'
     // ... more search options
   })
@@ -105,7 +105,7 @@ export const Search: FC<SearchProps> = ({
           return
         }
       }
-      const { results } = await window.pagefind.search<PagefindResult>(value)
+      const { results } = await window.pagefind!.search<PagefindResult>(value)
       const data = await Promise.all(results.map(o => o.data()))
 
       setResults(
@@ -131,12 +131,13 @@ export const Search: FC<SearchProps> = ({
   useEffect(() => {
     function handleKeyDown(event: globalThis.KeyboardEvent) {
       const input = inputRef.current
-      const activeElement = document.activeElement as HTMLElement
+      const { activeElement } = document
       const tagName = activeElement?.tagName.toLowerCase()
       if (
         !input ||
         !tagName ||
         INPUTS.has(tagName) ||
+        // @ts-expect-error -- fixme
         activeElement?.isContentEditable
       )
         return
diff --git a/packages/nextra/src/client/hocs/with-github-alert.tsx b/packages/nextra/src/client/hocs/with-github-alert.tsx
index b811b3ea42..d1091ba5bc 100644
--- a/packages/nextra/src/client/hocs/with-github-alert.tsx
+++ b/packages/nextra/src/client/hocs/with-github-alert.tsx
@@ -26,7 +26,9 @@ export function withGitHubAlert(
     if (Array.isArray(props.children)) {
       const str = props.children[1].props.children
       if (typeof str === 'string') {
-        const alertName = str.match(GITHUB_ALERT_RE)?.groups?.name.toLowerCase()
+        const alertName = str
+          .match(GITHUB_ALERT_RE)
+          ?.groups?.name!.toLowerCase()
 
         if (alertName) {
           if (!GITHUB_ALERT_TYPES.has(alertName)) {
@@ -39,7 +41,7 @@ export function withGitHubAlert(
             type: alertName as T,
             children: [
               <b key={0}>
-                {alertName[0].toUpperCase()}
+                {alertName[0]!.toUpperCase()}
                 {alertName.slice(1)}
               </b>,
               ...props.children.slice(2)
diff --git a/packages/nextra/src/client/mdx-components/pre/copy-to-clipboard.tsx b/packages/nextra/src/client/mdx-components/pre/copy-to-clipboard.tsx
index 2ad20219a4..13e9200cfd 100644
--- a/packages/nextra/src/client/mdx-components/pre/copy-to-clipboard.tsx
+++ b/packages/nextra/src/client/mdx-components/pre/copy-to-clipboard.tsx
@@ -23,10 +23,6 @@ export const CopyToClipboard: FC<ComponentProps<'button'>> = props => {
     ComponentProps<'button'>['onClick']
   > = async event => {
     setCopied(true)
-    if (!navigator.clipboard) {
-      console.error('Access to clipboard rejected!')
-      return
-    }
     const container = event.currentTarget.parentNode!.parentNode!
     const content = container.querySelector('pre code')?.textContent || ''
     try {
diff --git a/packages/nextra/src/client/normalize-pages.ts b/packages/nextra/src/client/normalize-pages.ts
index d064df700f..2f67eb3ee3 100644
--- a/packages/nextra/src/client/normalize-pages.ts
+++ b/packages/nextra/src/client/normalize-pages.ts
@@ -78,6 +78,7 @@ type DocsItem = (MdxFile | FolderWithoutChildren) & {
 function findFirstRoute(items: DocsItem[]): string | undefined {
   for (const item of items) {
     if (item.route) return item.route
+    // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition -- fixme
     if (item.children) {
       const route = findFirstRoute(item.children)
       if (route) return route
@@ -118,10 +119,10 @@ export function normalizePages({
   const flatDocsDirectories: DocsItem[] = []
   // Page directories
   const topLevelNavbarItems: (PageItem | MenuItem)[] = []
-
-  const meta = 'data' in list[0] ? (list[0].data as MetaType) : {}
+  const firstItem = list[0]! // always exists
+  const meta = 'data' in firstItem ? (firstItem.data as MetaType) : {}
   // Normalize items based on files and _meta.json.
-  const items = ('data' in list[0] ? list.slice(1) : list) as (
+  const items = ('data' in firstItem ? list.slice(1) : list) as (
     | (Folder & { frontMatter?: FrontMatter })
     | MdxFile
   )[]
@@ -209,6 +210,7 @@ export function normalizePages({
     if (normalizedChildren) {
       // If the active item is in its children
       if (
+        // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition -- fixme
         normalizedChildren.activeIndex !== undefined &&
         normalizedChildren.activeType !== undefined
       ) {
@@ -293,6 +295,7 @@ export function normalizePages({
 
     if (type === 'doc' && display === 'children') {
       // Hide the directory itself and treat all its children as pages
+      // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition -- fixme
       if (docsItem.children) {
         // @ts-expect-error -- fixme
         directories.push(...docsItem.children)
diff --git a/packages/nextra/src/env.d.ts b/packages/nextra/src/env.d.ts
index 9ce9ff07f6..17710ae4be 100644
--- a/packages/nextra/src/env.d.ts
+++ b/packages/nextra/src/env.d.ts
@@ -1,13 +1,15 @@
 declare namespace globalThis {
-  var pagefind: {
-    search: <T>(query: string) => Promise<{
-      results: {
-        data: () => Promise<T>
-        id: string
-      }[]
-    }>
-    options: (opts: Record<string, unknown>) => Promise<void>
-  }
+  var pagefind:
+    | {
+        search: <T>(query: string) => Promise<{
+          results: {
+            data: () => Promise<T>
+            id: string
+          }[]
+        }>
+        options: (opts: Record<string, unknown>) => Promise<void>
+      }
+    | undefined
 }
 
 declare module '*.svg' {
diff --git a/packages/nextra/src/server/__tests__/fixture/page-maps/folder-without-markdown-files/test.ts b/packages/nextra/src/server/__tests__/fixture/page-maps/folder-without-markdown-files/test.ts
index e69de29bb2..97a46ca777 100644
--- a/packages/nextra/src/server/__tests__/fixture/page-maps/folder-without-markdown-files/test.ts
+++ b/packages/nextra/src/server/__tests__/fixture/page-maps/folder-without-markdown-files/test.ts
@@ -0,0 +1 @@
+// eslint-disable-next-line unicorn/no-empty-file -- For test case
diff --git a/packages/nextra/src/server/__tests__/latex.test.ts b/packages/nextra/src/server/__tests__/latex.test.ts
index 5c59660bdf..919f6ad1d4 100644
--- a/packages/nextra/src/server/__tests__/latex.test.ts
+++ b/packages/nextra/src/server/__tests__/latex.test.ts
@@ -110,7 +110,7 @@ describe('LaTeX', () => {
       latex: { renderer: 'mathjax' }
     } as const
 
-    const INLINE_MATH = '$a=\\sqrt{b^2 + c^2}$'
+    const INLINE_MATH = String.raw`$a=\sqrt{b^2 + c^2}$`
     const MATH_LANG = '```math\nx^2\n```'
 
     it('should convert math inline', async () => {
diff --git a/packages/nextra/src/server/__tests__/normalize.test.ts b/packages/nextra/src/server/__tests__/normalize.test.ts
index b67db146eb..a88ab700ef 100644
--- a/packages/nextra/src/server/__tests__/normalize.test.ts
+++ b/packages/nextra/src/server/__tests__/normalize.test.ts
@@ -335,9 +335,9 @@ describe('normalize-page', () => {
       route: '/docs/bar'
     })
     const { docsDirectories } = normalizedResult
-    expect(docsDirectories[0].name).toBe('_')
-    expect(docsDirectories[1].route).toBe('/docs/bar')
-    expect(docsDirectories[2].route).toBe('/foo')
+    expect(docsDirectories[0]!.name).toBe('_')
+    expect(docsDirectories[1]!.route).toBe('/docs/bar')
+    expect(docsDirectories[2]!.route).toBe('/foo')
   })
 
   // https://github.com/shuding/nextra/issues/3581
diff --git a/packages/nextra/src/server/compile-metadata.ts b/packages/nextra/src/server/compile-metadata.ts
index 0509871130..30193d58ce 100644
--- a/packages/nextra/src/server/compile-metadata.ts
+++ b/packages/nextra/src/server/compile-metadata.ts
@@ -36,7 +36,7 @@ export async function compileMetadata(
     ],
     recmaPlugins: [
       () => (ast: Program) => {
-        const [importReact] = ast.body
+        const importReact = ast.body[0]! // always exist
 
         ast.body = ast.body.filter(
           node =>
diff --git a/packages/nextra/src/server/compile.ts b/packages/nextra/src/server/compile.ts
index b05624505c..9c43ed9d15 100644
--- a/packages/nextra/src/server/compile.ts
+++ b/packages/nextra/src/server/compile.ts
@@ -39,7 +39,7 @@ type Processor = ReturnType<typeof createProcessor>
 
 const cachedCompilerForFormat: Record<
   `${NonNullable<ProcessorOptions['format']>}:${boolean}`,
-  Processor
+  Processor | void
 > = Object.create(null)
 
 type MdxOptions = NextraConfig['mdxOptions'] &
@@ -111,7 +111,7 @@ export async function compileMdx(
   const compiler =
     !useCachedCompiler || isRemoteContent
       ? createCompiler()
-      : (cachedCompilerForFormat[`${format}:${isPageImport}`] ??=
+      : (cachedCompilerForFormat[`${format}:${isPageImport}`] ||=
           createCompiler())
   const processor = compiler()
 
@@ -119,7 +119,7 @@ export async function compileMdx(
     const vFile = await processor.process(fileCompatible)
     const rawJs = (vFile.value as string)
       // https://github.com/shuding/nextra/issues/1032
-      .replaceAll('__esModule', '_\\_esModule')
+      .replaceAll('__esModule', String.raw`_\_esModule`)
     return rawJs
   } catch (error) {
     console.error(`[nextra] Error compiling ${filePath}.`)
@@ -210,7 +210,7 @@ export async function compileMdx(
       recmaPlugins: [
         ...(recmaPlugins || []),
         [recmaRewrite, { isPageImport, isRemoteContent }] satisfies Pluggable
-      ].filter(v => !!v)
+      ]
     })
   }
 }
diff --git a/packages/nextra/src/server/fetch-filepaths-from-github.ts b/packages/nextra/src/server/fetch-filepaths-from-github.ts
index 957082bde0..509e611f60 100644
--- a/packages/nextra/src/server/fetch-filepaths-from-github.ts
+++ b/packages/nextra/src/server/fetch-filepaths-from-github.ts
@@ -25,6 +25,7 @@ export async function fetchFilePathsFromGitHub({
       '❌ GitHub API rate limit exceeded, skipping…',
       JSON.stringify(data, null, 2)
     )
+    // eslint-disable-next-line unicorn/no-process-exit -- This file is a CLI
     process.exit(0)
   }
   const filePaths = (data.tree as { path: string }[])
diff --git a/packages/nextra/src/server/index.ts b/packages/nextra/src/server/index.ts
index 38c59f89a6..04e59dd241 100644
--- a/packages/nextra/src/server/index.ts
+++ b/packages/nextra/src/server/index.ts
@@ -27,10 +27,10 @@ const GET_PAGE_MAP_PATH = '/nextra/dist/server/page-map/get.js'
 const PAGE_MAP_PLACEHOLDER_PATH = '/nextra/dist/server/page-map/placeholder.js'
 
 const GET_PAGE_MAP_RE = new RegExp(
-  GET_PAGE_MAP_PATH.replaceAll('/', SEP).replaceAll('.', '\\.')
+  GET_PAGE_MAP_PATH.replaceAll('/', SEP).replaceAll('.', String.raw`\.`)
 )
 const PAGE_MAP_PLACEHOLDER_RE = new RegExp(
-  PAGE_MAP_PLACEHOLDER_PATH.replaceAll('/', SEP).replaceAll('.', '\\.')
+  PAGE_MAP_PLACEHOLDER_PATH.replaceAll('/', SEP).replaceAll('.', String.raw`\.`)
 )
 const CONTENT_DIR = getContentDirectory()
 
@@ -152,7 +152,10 @@ const nextra: Nextra = nextraConfig => {
           config.watchOptions = {
             ...config.watchOptions,
             ignored: new RegExp(
-              ignored.replace('(\\.(git|next)|node_modules)', '\\.(git|next)')
+              ignored.replace(
+                String.raw`(\.(git|next)|node_modules)`,
+                String.raw`\.(git|next)`
+              )
             )
           }
         }
@@ -188,6 +191,7 @@ const nextra: Nextra = nextraConfig => {
                 // issuer, which can be anything as long as it's not empty string.
                 // When the issuer is `null`, it means that it can be imported via a
                 // runtime import call such as `import('...')`.
+                // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition -- types are wrong, value can be null
                 issuer: request => request === null || !!request,
                 use: [options.defaultLoaders.babel, loader]
               }
diff --git a/packages/nextra/src/server/loader.ts b/packages/nextra/src/server/loader.ts
index f7938f9685..2e5137d530 100644
--- a/packages/nextra/src/server/loader.ts
+++ b/packages/nextra/src/server/loader.ts
@@ -99,7 +99,7 @@ export async function loader(
     )
     return convertPageMapToJs({ pageMap, mdxPages, globalMetaPath })
   }
-  // We pass `locales` only for `page-map/get.ts`
+  // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition -- We pass `locales` only for `page-map/get.ts`
   if (locales) {
     return replaceDynamicResourceQuery(
       source,
diff --git a/packages/nextra/src/server/locales.ts b/packages/nextra/src/server/locales.ts
index b4772b4139..4a396cd266 100644
--- a/packages/nextra/src/server/locales.ts
+++ b/packages/nextra/src/server/locales.ts
@@ -46,7 +46,7 @@ export function middleware(request: NextRequest) {
 
   if (requestLocale !== cookieLocale) {
     const response = NextResponse.next()
-    response.cookies.set(COOKIE_NAME, requestLocale)
+    response.cookies.set(COOKIE_NAME, requestLocale!)
     return response
   }
 }
diff --git a/packages/nextra/src/server/page-map/merge-meta-with-page-map.ts b/packages/nextra/src/server/page-map/merge-meta-with-page-map.ts
index dd77553be1..9cba1ebd2a 100644
--- a/packages/nextra/src/server/page-map/merge-meta-with-page-map.ts
+++ b/packages/nextra/src/server/page-map/merge-meta-with-page-map.ts
@@ -61,7 +61,7 @@ export function mergeMetaWithPageMap<T extends Folder | PageMapItem[]>(
     }
     return restParent
   })
-  const hasMeta = 'data' in result[0]
+  const hasMeta = 'data' in result[0]!
   if (hasMeta) {
     // @ts-expect-error fixme
     const childRoute = result[1].route
diff --git a/packages/nextra/src/server/page-map/normalize.ts b/packages/nextra/src/server/page-map/normalize.ts
index 1ce7e31666..dd04475398 100644
--- a/packages/nextra/src/server/page-map/normalize.ts
+++ b/packages/nextra/src/server/page-map/normalize.ts
@@ -78,27 +78,25 @@ function sortFolder(pageMap: PageMapItem[] | Folder) {
   for (const [index, metaKey] of metaKeys
     .filter(key => key !== '*')
     .entries()) {
-    const metaItem = meta[metaKey]
+    const metaItem = meta[metaKey]!
     const item = items.find(item => item.name === metaKey)
-    if (metaItem.type === 'menu') {
-      if (item) {
+    if (metaItem.type === 'menu' && item) {
+      // @ts-expect-error fixme
+      item.items = metaItem.items
+
+      // Validate menu items, local page should exist
+      const { children } = items.find(
+        (i): i is Folder<MdxFile> => i.name === metaKey
+      )!
+      for (const [key, value] of Object.entries(
         // @ts-expect-error fixme
-        item.items = metaItem.items
-
-        // Validate menu items, local page should exist
-        const { children } = items.find(
-          (i): i is Folder<MdxFile> => i.name === metaKey
-        )!
-        for (const [key, value] of Object.entries(
-          // @ts-expect-error fixme
-          item.items as Record<string, { title: string; href?: string }>
-        )) {
-          if (!value.href && children.every(i => i.name !== key)) {
-            throw new Error(
-              `Validation of "_meta" file has failed.
+        item.items as Record<string, { title: string; href?: string }>
+      )) {
+        if (!value.href && children.every(i => i.name !== key)) {
+          throw new Error(
+            `Validation of "_meta" file has failed.
 The field key "${metaKey}.items.${key}" in \`_meta\` file refers to a page that cannot be found, remove this key from "_meta" file.`
-            )
-          }
+          )
         }
       }
     }
diff --git a/packages/nextra/src/server/page-map/placeholder.ts b/packages/nextra/src/server/page-map/placeholder.ts
index e69de29bb2..d3b634046f 100644
--- a/packages/nextra/src/server/page-map/placeholder.ts
+++ b/packages/nextra/src/server/page-map/placeholder.ts
@@ -0,0 +1 @@
+// eslint-disable-next-line unicorn/no-empty-file -- Should exist; will be overridden by Webpack
diff --git a/packages/nextra/src/server/page-map/to-page-map.ts b/packages/nextra/src/server/page-map/to-page-map.ts
index f3c2eafe43..66bae7d706 100644
--- a/packages/nextra/src/server/page-map/to-page-map.ts
+++ b/packages/nextra/src/server/page-map/to-page-map.ts
@@ -8,6 +8,7 @@ interface NestedMap {
 type StringMap = Record<string, string>
 
 const createNested = (prevValue: NestedMap, currVal: string) =>
+  // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition -- value can be `undefined`
   (prevValue[currVal] ||= {})
 
 const APP_DIR_SUFFIX_RE = /^(src\/)?app\//
@@ -55,10 +56,12 @@ export function convertToPageMap({
   }
 
   for (const path of Object.keys(metaFiles)) {
+    // eslint-disable-next-line unicorn/no-array-callback-reference
     path.split('/').reduce(createNested, nestedMap)
   }
   for (const path of Object.keys(pages)) {
     const key = path && `${path}/`
+    // eslint-disable-next-line unicorn/no-array-callback-reference
     key.split('/').reduce(createNested, nestedMap)
   }
 
diff --git a/packages/nextra/src/server/recma-plugins/recma-rewrite.ts b/packages/nextra/src/server/recma-plugins/recma-rewrite.ts
index 96a1227056..322ca4f0bc 100644
--- a/packages/nextra/src/server/recma-plugins/recma-rewrite.ts
+++ b/packages/nextra/src/server/recma-plugins/recma-rewrite.ts
@@ -22,8 +22,8 @@ export const recmaRewrite: Plugin<
       node =>
         node.type === 'VariableDeclaration' &&
         node.kind === 'const' &&
-        node.declarations[0].id.type === 'Identifier' &&
-        node.declarations[0].id.name === 'MDXLayout'
+        node.declarations[0]!.id.type === 'Identifier' &&
+        node.declarations[0]!.id.name === 'MDXLayout'
     )
     // Remote MDX
     if (isRemoteContent) {
diff --git a/packages/nextra/src/server/rehype-plugins/rehype-better-react-mathjax.ts b/packages/nextra/src/server/rehype-plugins/rehype-better-react-mathjax.ts
index e26d176c5b..eb8dadb831 100644
--- a/packages/nextra/src/server/rehype-plugins/rehype-better-react-mathjax.ts
+++ b/packages/nextra/src/server/rehype-plugins/rehype-better-react-mathjax.ts
@@ -74,8 +74,8 @@ function wrapInBraces(
 ): string {
   const { inlineMath, displayMath } = options.config?.tex || {}
 
-  const inlineBraces = inlineMath?.[0] || ['\\(', '\\)']
-  const displayBraces = displayMath?.[0] || ['\\[', '\\]']
+  const inlineBraces = inlineMath?.[0] || [String.raw`\(`, String.raw`\)`]
+  const displayBraces = displayMath?.[0] || [String.raw`\[`, String.raw`\]`]
   const [before, after] = mathInline ? inlineBraces : displayBraces
   return `${before}${source}${after}`
 }
@@ -116,12 +116,13 @@ export const rehypeBetterReactMathjax: Plugin<
       hasMathJax = true
     })
 
+    // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition -- fixme
     if (!hasMathJax) return
 
     const mdxjsEsmNodes = []
     const rest: ElementContent[] = []
     for (const child of ast.children) {
-      if ((child as MdxjsEsm).type === 'mdxjsEsm') {
+      if (child.type === 'mdxjsEsm') {
         mdxjsEsmNodes.push(child)
       } else {
         rest.push(child as any)
diff --git a/packages/nextra/src/server/rehype-plugins/rehype-extract-toc-content.ts b/packages/nextra/src/server/rehype-plugins/rehype-extract-toc-content.ts
index 9641ad9091..7f1fd7ea4a 100644
--- a/packages/nextra/src/server/rehype-plugins/rehype-extract-toc-content.ts
+++ b/packages/nextra/src/server/rehype-plugins/rehype-extract-toc-content.ts
@@ -28,7 +28,7 @@ export const rehypeExtractTocContent: Plugin<[], Root> = () => (ast, file) => {
       } satisfies SpreadElement
     }
 
-    const node = TocMap[name.id]
+    const node = TocMap[name.id]!
 
     const isTextOnly = node.children.every(child => child.type === 'text')
 
diff --git a/packages/nextra/src/server/rehype-plugins/rehype.ts b/packages/nextra/src/server/rehype-plugins/rehype.ts
index 840c458571..0f5e96facb 100644
--- a/packages/nextra/src/server/rehype-plugins/rehype.ts
+++ b/packages/nextra/src/server/rehype-plugins/rehype.ts
@@ -50,7 +50,7 @@ export const rehypeParseCodeMeta: Plugin<
   ast => {
     visit(ast, { tagName: 'pre' }, (node: PreElement) => {
       const [codeEl] = node.children as Element[]
-      const { meta = '' } = codeEl.data || {}
+      const { meta = '' } = codeEl!.data || {}
 
       node.__filename = meta!.match(CODE_BLOCK_FILENAME_RE)?.[1]
       node.properties['data-filename'] = node.__filename
@@ -93,7 +93,7 @@ export const rehypeAttachCodeMeta: Plugin<
         delete preEl.properties['data-theme']
 
         if (preEl.tagName === 'pre') {
-          const [codeEl] = preEl.children as Element[]
+          const codeEl = preEl.children[0] as Element
           delete codeEl.properties['data-theme']
           delete codeEl.properties['data-language']
 
diff --git a/packages/nextra/src/server/remark-plugins/remark-mdx-title.ts b/packages/nextra/src/server/remark-plugins/remark-mdx-title.ts
index d2d5c2b529..486e4d8d77 100644
--- a/packages/nextra/src/server/remark-plugins/remark-mdx-title.ts
+++ b/packages/nextra/src/server/remark-plugins/remark-mdx-title.ts
@@ -17,7 +17,7 @@ export function isExportNode(
   varName: string
 ): node is MdxjsEsm {
   if (node.type !== 'mdxjsEsm') return false
-  const [n] = node.data!.estree!.body
+  const n = node.data!.estree!.body[0]!
 
   if (n.type !== 'ExportNamedDeclaration') return false
 
diff --git a/packages/nextra/src/server/twoslash.ts b/packages/nextra/src/server/twoslash.ts
index 7d01d73be9..bb07a760fe 100644
--- a/packages/nextra/src/server/twoslash.ts
+++ b/packages/nextra/src/server/twoslash.ts
@@ -52,12 +52,14 @@ function renderMarkdownInline(
     context === 'tag:param' ? md.replace(/^(?<link>[\w$-]+)/, '`$1` ') : md
 
   const children = renderMarkdown.call(this, text)
+  const [firstChild] = children
   if (
     children.length === 1 &&
-    children[0].type === 'element' &&
-    children[0].tagName === 'p'
+    firstChild &&
+    firstChild.type === 'element' &&
+    firstChild.tagName === 'p'
   )
-    return children[0].children
+    return firstChild.children
   return children
 }
 
diff --git a/packages/nextra/tsconfig.json b/packages/nextra/tsconfig.json
index 73de49624f..4c6dc4ffba 100644
--- a/packages/nextra/tsconfig.json
+++ b/packages/nextra/tsconfig.json
@@ -15,7 +15,8 @@
     "paths": {
       "unified": ["./node_modules/unified"]
     },
-    "resolveJsonModule": true
+    "resolveJsonModule": true,
+    "noUncheckedIndexedAccess": true
   },
   "exclude": ["dist"]
 }
diff --git a/packages/nextra/tsup.config.ts b/packages/nextra/tsup.config.ts
index a08dc09968..7bcbe66dbf 100644
--- a/packages/nextra/tsup.config.ts
+++ b/packages/nextra/tsup.config.ts
@@ -10,7 +10,7 @@ import { CWD, IS_PRODUCTION } from './src/server/constants.js'
 const SEP = path.sep === '/' ? '/' : '\\\\'
 
 const CLIENT_FILE_RE = new RegExp(
-  '/nextra/src/client/.*\\.tsx?$'.replaceAll('/', SEP)
+  String.raw`/nextra/src/client/.*\.tsx?$`.replaceAll('/', SEP)
 )
 
 export default defineConfig({