TContext is not inferred from onMutate

[jansedlon]

Describe the bug
Type of TContext in onError is not inferred from returned value of onMutate

To Reproduce
Steps to reproduce the behavior:
Go to https://codesandbox.io/s/gracious-newton-crlx9?file=/src/App.tsx

Expected behavior
TContext to be inferred from onMutate return value

React-Query

• Version: 3.5.11

Additional context
I'm not sure if there's something that I'm missing but the provided CodeSandbox should be almost the same as the one from documentation.. Optimistic Updates with Typescript. In React-Query's codesandbox it is inferred, in my code it's not.

[TkDodo]

for some reason, you need to add types to onMutate so that the types are correctly inferred in onSuccess :/

updated example: https://codesandbox.io/s/silly-aryabhata-gnc1h?file=/src/App.tsx

I found this out while making the TS example for the docs, see the PR discussion: #1366 (comment)

[jansedlon]

Hmm.. That's really interesting. Typescript knows that type for sure but can't pass it to TContext. Anyway, that's much more elegant solution than mine (I was specifying the whole context type). Thanks! 👍