fix(eslint-plugin): [prefer-optional-chain] address multipart nullish checks false positive

[kirkwaiblinger]

PR Checklist

• Addresses an existing open issue: fixes Bug: [prefer-optional-chain] Issue with check on null and undefined #8380
• That issue was marked as accepting prs
• Steps in Contributing were taken

Overview

Basically the trouble is that the rule checks "am I in a subsequence of logical operands that are candidates for optional chaining that is more than one unit long?", assuming that a nullish check will be the first element in that chain and subsequent elements will be chainable expressions. However, a nullish check such as a !== null && a !== undefined takes up more than one element in that subsequence, since it is two comparisons. When checking if the length is greater than 1, we get a false positive.

The code change groups the subsequence so that a !== null && a !== undefined get treated as a single unit when checking whether to report.

my brain hurts.

[typescript-eslint]

Thanks for the PR, @kirkwaiblinger!

typescript-eslint is a 100% community driven project, and we are incredibly grateful that you are contributing to that community.

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.

Thanks again!

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.23%. Comparing base (858c9a6) to head (f2877e7).
Report is 10 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8678      +/-   ##
==========================================
+ Coverage   87.21%   87.23%   +0.01%     
==========================================
  Files         251      251              
  Lines       12305    12320      +15     
  Branches     3880     3884       +4     
==========================================
+ Hits        10732    10747      +15     
  Misses       1303     1303              
  Partials      270      270              

Flag	Coverage Δ
unittest	87.23% <100.00%> (+0.01%)	⬆️

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

Files	Coverage Δ
.../rules/prefer-optional-chain-utils/analyzeChain.ts	100.00% <100.00%> (ø)

... and 3 files with indirect coverage changes

[JoshuaKGoldberg]

Wow, what a tricky set of situations. +1 to the implementation, nicely done! 🔥