fix(typescript-eslint): fix type errors when using exactOptionalPropertyTypes

[abrahamguo]

PR Checklist

• Addresses an existing open issue: fixes Bug: Type error when using ConfigWithExtends (eslint-plugin-playwright) #8782
• That issue was marked as accepting prs
• Steps in Contributing were taken

Overview

Support exactOptionalPropertyTypes: true

[typescript-eslint]

Thanks for the PR, @abrahamguo!

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The core maintainers work on this in their personal time, so please understand that it may not be possible for them to review your work immediately.

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[bradzacher]

Thanks for this!
Let's add a new integration test for this to.make sure it works and make sure we don't cause a regression.

Here is the existing integration test:
https://github.com/typescript-eslint/typescript-eslint/tree/main/packages/integration-tests/fixtures/flat-config-types

Let's add a new one that uses exactOptionalPropertyTypes

Let's also update the old (and new one) to include eslint-plugin-playwright so that we're testing more cases.

[abrahamguo]

@bradzacher Unfortunately, fixing the original type error in the linked issue revealed a series of about 20 more type errors of various nested properties in the same fashion, so I had to add a lot more | undefineds. Do you have any objection to this?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.01%. Comparing base (d5615d7) to head (479caba).
Report is 21 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8786      +/-   ##
==========================================
+ Coverage   87.36%   88.01%   +0.64%     
==========================================
  Files         255      405     +150     
  Lines       12498    14076    +1578     
  Branches     3923     4121     +198     
==========================================
+ Hits        10919    12389    +1470     
- Misses       1304     1382      +78     
- Partials      275      305      +30     

Flag	Coverage Δ
unittest	88.01% <ø> (+0.64%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

see 150 files with indirect coverage changes

[bradzacher]

thanks for doing this! I hate that we need to do this due to the @types/eslint types but it is what it is.