Bump typescript to ^4.8.2

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
typescript (source)	^4.6.4 -> ^4.8.2

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[mnajdova]

@michaldudak could you help out with this one? It currently fails on the @mui/base package check, but to be honest I have no idea what causes this:

@mui/base: D:\workspace\mui\node_modules\typescript\lib\tsc.js:96887
@mui/base:                 throw e;
@mui/base:                 ^
@mui/base: Error: Debug Failure. Expected [object Object] === [object Object]. Parameter symbol already has a cached type which differs from newly assigned type
@mui/base:     at assignParameterType (D:\workspace\mui\node_modules\typescript\lib\tsc.js:64861:26)
@mui/base:     at assignContextualParameterTypes (D:\workspace\mui\node_modules\typescript\lib\tsc.js:64826:21)
@mui/base:     at contextuallyCheckFunctionExpressionOrObjectLiteralMethod (D:\workspace\mui\node_modules\typescript\lib\tsc.js:65228:29)
@mui/base:     at checkFunctionExpressionOrObjectLiteralMethod (D:\workspace\mui\node_modules\typescript\lib\tsc.js:65207:13)
@mui/base:     at checkExpressionWorker (D:\workspace\mui\node_modules\typescript\lib\tsc.js:66804:28)
@mui/base:     at checkExpression (D:\workspace\mui\node_modules\typescript\lib\tsc.js:66706:38)
@mui/base:     at checkExpressionWithContextualType (D:\workspace\mui\node_modules\typescript\lib\tsc.js:66395:28)
@mui/base:     at inferTypeArguments (D:\workspace\mui\node_modules\typescript\lib\tsc.js:62905:39)
@mui/base:     at chooseOverload (D:\workspace\mui\node_modules\typescript\lib\tsc.js:63565:53)
@mui/base:     at resolveCall (D:\workspace\mui\node_modules\typescript\lib\tsc.js:63402:26)
@mui/base: info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
@mui/base: error Command failed with exit code 1.

I could find this related issue if it helps - microsoft/TypeScript#49383

[michaldudak]

Sure, I'll take a look at it.

[michaldudak]

I spent some time today trying to find statements that cause this error, so I can work around it, but I couldn't solve this.
I hope the corresponding TS issue will be fixed and it'll make our codebase buildable again. So far, I'm getting the same error with TS 4.8.0-beta

[mnajdova]

Alright, let's wait then.

[michaldudak]

Good news - TypeScript 4.8 RC does not show this error. Upgrading to it won't be effortless, though, as some checks are now more strict and our code fails in a couple of places (mostly in Base). I'll wait until it's stable before fixing the issues, though.

[michaldudak]

There were a couple of type changes needed due to breaking changes TypeScript 4.8 has introduced.
@siriwatknp and @mnajdova - you may want to review them as they touch the areas you own. I used my best judgment, but as I'm not very familiar with some parts of the code, feel free to correct me.

The good part is that the new TS is better at inferring types and it allowed us to remove some expect-errors from type tests.

[siriwatknp]

👍 Looks good to me. I pushed one change that removed the casting with proper extends, please check the latest commit.

[michaldudak]

@mui/x, @mui/toolpad right after I hit "merge" I realized that you might also be affected by this change. Could you please check if it causes any issues on your side?

[flaviendelangle]

It does break on our side but we'll fix to keep up to date with TS 👍

[Janpot]

I see we have a few breaks on our end as well, but good incentive to update typescript on our side. Will fix asap.

[michaldudak]

Sorry for such a late notice

[Janpot]

Well, I just noticed our docs workspace was using typescript 3.8.3 😄