[useAutocomplete] Pass only valid values for the getOptionLabel prop

[rangoo94]

The getOptionLabel prop shouldn't be called with fallback values, as it will not match the TypeScript's contract for generic getOptionLabel value.

Fixes #36045

• I have followed (at least) the PR section of the contributing guide.

Before: https://codesandbox.io/s/angry-tree-2jcp3o?file=/src/App.tsx

After: https://codesandbox.io/s/frosty-tdd-euyttl?file=/src/App.tsx

[mui-bot]

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[ZeeshanTamboli]

@rangoo94 Thanks for the PR. Can you add a test showcasing and covering the fix for the issue provided in the reproduction?

[rangoo94]

@ZeeshanTamboli, sure, not a problem - I added the unit test for regression.

[ZeeshanTamboli]

Let's not check with strict equality, in case value is undefined or empty string '' using a controlled Autocomplete.

Suggested change

	const label1 = value1 === null ? '' : getOptionLabel(value1);
	const label2 = value2 === null ? '' : getOptionLabel(value2);
	const label1 = !value1 ? '' : getOptionLabel(value1);
	const label2 = !value2 ? '' : getOptionLabel(value2);

[rangoo94]

It will have small edge cases, i.e. false will be treated equally to null. I will do that though, as I believe that it will be ultimately rare, and even then the inconvenience will be low 👍

[ZeeshanTamboli]

In most cases, or perhaps never, value will not be false. 

[rangoo94]

@ZeeshanTamboli Thanks, I have applied the expected changes.

[ZeeshanTamboli]

@rangoo94 It's a great first pull request on MUI 👌 Thank you for working on it!