chore: upgrade eslint to v9

[jrmajor]

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Tests and linting

• Run the tests with pnpm test and lint the project with pnpm lint

[changeset-bot]

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Latest commit: 08c7863

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[vane]

I think it broke typescript support because of this typescript-eslint issue
typescript-eslint/typescript-eslint#8211

[benmccann]

That thread said it should work fine besides give you a peer dependency warning. Are you encountering a specific issue with it?

[vane]

That thread said it should work fine besides give you a peer dependency warning. Are you encountering a specific issue with it?

It indeed gives warning after I bumbed from 8.57.0 to 9.0.0

on freshly created app with 9.0.0 npm install fails with error

# npm resolution error report

While resolving: typescript-eslint@7.6.0
Found: eslint@9.0.0
node_modules/eslint
  dev eslint@"^9.0.0" from the root project
  peer eslint@"^6.0.0 || ^7.0.0 || >=8.0.0" from @eslint-community/eslint-utils@4.4.0
  node_modules/@eslint-community/eslint-utils
    @eslint-community/eslint-utils@"^4.2.0" from eslint@9.0.0
    @eslint-community/eslint-utils@"^4.4.0" from eslint-plugin-svelte@2.37.0
    node_modules/eslint-plugin-svelte
      dev eslint-plugin-svelte@"^2.36.0" from the root project
    @eslint-community/eslint-utils@"^4.4.0" from @typescript-eslint/utils@7.6.0
    node_modules/typescript-eslint/node_modules/@typescript-eslint/utils
      @typescript-eslint/utils@"7.6.0" from typescript-eslint@7.6.0
      node_modules/typescript-eslint
        dev typescript-eslint@"^7.6.0" from the root project
      @typescript-eslint/utils@"7.6.0" from @typescript-eslint/eslint-plugin@7.6.0
      node_modules/typescript-eslint/node_modules/@typescript-eslint/eslint-plugin
        @typescript-eslint/eslint-plugin@"7.6.0" from typescript-eslint@7.6.0
        node_modules/typescript-eslint
          dev typescript-eslint@"^7.6.0" from the root project
      @typescript-eslint/utils@"7.6.0" from @typescript-eslint/type-utils@7.6.0
      node_modules/typescript-eslint/node_modules/@typescript-eslint/eslint-plugin/node_modules/@typescript-eslint/type-utils
        @typescript-eslint/type-utils@"7.6.0" from @typescript-eslint/eslint-plugin@7.6.0
        node_modules/typescript-eslint/node_modules/@typescript-eslint/eslint-plugin
          @typescript-eslint/eslint-plugin@"7.6.0" from typescript-eslint@7.6.0
          node_modules/typescript-eslint
            dev typescript-eslint@"^7.6.0" from the root project
  peer eslint@">=6.0.0" from eslint-compat-utils@0.5.0
  node_modules/eslint-compat-utils
    eslint-compat-utils@"^0.5.0" from eslint-plugin-svelte@2.37.0
    node_modules/eslint-plugin-svelte
      dev eslint-plugin-svelte@"^2.36.0" from the root project
  peer eslint@">=7.0.0" from eslint-config-prettier@9.1.0
  node_modules/eslint-config-prettier
    dev eslint-config-prettier@"^9.1.0" from the root project
  peer eslint@"^7.0.0 || ^8.0.0-0 || ^9.0.0-0" from eslint-plugin-svelte@2.37.0
  node_modules/eslint-plugin-svelte
    dev eslint-plugin-svelte@"^2.36.0" from the root project

Could not resolve dependency:
peer eslint@"^8.56.0" from typescript-eslint@7.6.0
node_modules/typescript-eslint
  dev typescript-eslint@"^7.6.0" from the root project

Conflicting peer dependency: eslint@8.57.0
node_modules/eslint
  peer eslint@"^8.56.0" from typescript-eslint@7.6.0
  node_modules/typescript-eslint
    dev typescript-eslint@"^7.6.0" from the root project

Fix the upstream dependency conflict, or retry
this command with --force or --legacy-peer-deps
to accept an incorrect (and potentially broken) dependency resolution.

[benmccann]

If you're talking about a freshly created app, you're posting on the wrong PR and in the wrong repository. You'd be talking about the create-svelte project that lives in the SvelteKit repository and was rolled back to eslint 8 earlier today

This PR only affects people contributing to Svelte itself