Revert "Feature: make return state(data, error and isValidating) readonly"

jest.config.js

@@ -12,7 +12,7 @@ module.exports = {
   globals: {
     'ts-jest': {
       tsconfig: 'test/tsconfig.json',
-      diagnostics: false,
+      diagnostics: process.env.CI,
     }
   },
 }

src/types.ts

@@ -148,10 +148,10 @@ export type SWRConfiguration<
 export type Key = ValueKey | (() => ValueKey)
 
 export interface SWRResponse<Data, Error> {
-  data?: Readonly<Data>
-  error?: Readonly<Error>
+  data?: Data
+  error?: Error
   mutate: KeyedMutator<Data>
-  isValidating: Readonly<boolean>
+  isValidating: boolean
 }
 
 export type KeyLoader<Data = any> =

test/use-swr-immutable.test.tsx

@@ -140,10 +140,7 @@ describe('useSWR - immutable', () => {
   })
 
   it('should not revalidate with revalidateIfStale disabled when key changes', async () => {
-    const fetcher = jest.fn(v => {
-      console.log(v)
-      return v
-    })
+    const fetcher = jest.fn(v => v)
 
     const key = createKey()
     const useData = (id: string) =>