Fixed unmounted component state update

[mccraveiro]

In my project I'm getting the following error with useQuery:

Warning: Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in %s.%s, a useEffect cleanup function,

After some debugging, I came into this line:

react-apollo/packages/hooks/src/utils/useBaseQuery.ts

Line 34 in 4bd40a9

Promise.resolve().then(forceUpdate);

Because of the re-render in a microtask this may cause the hook to update the state of an unmounted component. Adding a isMounted check fixed the issue.

I'm not sure how to add tests for this. Any suggestions?

[apollo-cla]

@mccraveiro: Thank you for submitting a pull request! Before we can merge it, you'll need to sign the Apollo Contributor License Agreement here: https://contribute.apollographql.com/

[mccraveiro]

@benjamn @hwillson Should I move this PR to the apollo-client repository? This patch will need to be applied on both.

[renanmav]

I tested and I can confirm that these changes work