initFocus doesn't not remove listeners when unmounting SWRConfig

[thgh]

Bug report

Description / Observed Behavior

I was looking through the source code but couldn't find the code where it calls the unsubscribe function that's returned in initFocus . It seems like it will never be called.

This is not a blocking issue, just an inconsistency in the docs/code.

Expected Behavior

It should call the function that's returned from initFocus() when unmounting the provider (SWRConfig).
OR
it should call the function that's returned from initFocus() when there are no active useSWR() hooks.

Repro Steps / Code Example

Derived from https://swr.vercel.app/docs/advanced/react-native#global-setup

<SWRConfig 
  value={{
    initFocus: () => {
      return () => alert('This function is never called')
    }
  }}
>
  <App>
</SWRConfig>

Additional Context

SWR version 1

Relevant code:

swr/src/utils/cache.ts

Lines 57 to 58 in 3285cc4

	if (!IS_SERVER) {
	opts.initFocus(

Mentioned in #417 (comment)

[shuding]

Thank you! We've just fixed it in #1449. 🎉

[Myzel394]

For me, initFocus is even never called at all