fix(eslint-plugin): [prefer-optional-chain] only look at left operand for requireNullish

[abrahamguo]

PR Checklist

• Addresses an existing open issue: fixes Bug: [prefer-optional-chain] doesn't report at all when requireNullish is true #8487
• That issue was marked as accepting prs
• Steps in Contributing were taken

Overview

As mentioned in the linked issue, requireNullish: true wrongly disables all checking for this rule. This is because it mistakenly applies the requireNullish logic to both the left and right operands, rather than only the left.

[typescript-eslint]

Thanks for the PR, @abrahamguo!

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.24%. Comparing base (716b783) to head (fd2b38f).
Report is 18 commits behind head on main.

❗ Current head fd2b38f differs from pull request most recent head 15d7dbc. Consider uploading reports for the commit 15d7dbc to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8559      +/-   ##
==========================================
- Coverage   88.02%   87.24%   -0.78%     
==========================================
  Files         405      252     -153     
  Lines       14089    12344    -1745     
  Branches     4125     3882     -243     
==========================================
- Hits        12402    10770    -1632     
+ Misses       1382     1305      -77     
+ Partials      305      269      -36     

Flag	Coverage Δ
unittest	87.24% <100.00%> (-0.78%)	⬇️

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)
...efer-optional-chain-utils/checkNullishAndReport.ts	100.00% <100.00%> (ø)
...efer-optional-chain-utils/gatherLogicalOperands.ts	100.00% <ø> (ø)
...s/eslint-plugin/src/rules/prefer-optional-chain.ts	97.61% <100.00%> (+0.05%)	⬆️

... and 176 files with indirect coverage changes

[auvred]

I haven't looked deep into the source code of the rule yet, so I can't suggest any complete solutions. Requesting changes to prevent one potential bug and to improve the tests.

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It also looks like you linked the wrong issue in the PR description. I believe you should link this one: #8487. Right?

[auvred]

The overall code changes look great to me! Although, I haven't gotten deep enough into the rule code to 100% understand the logic yet. I'll try to take the time to figure out how it works internally, and then I can do a more thorough review 🙂

[auvred]

Mostly LGTM!

But there is conflict with main branch in packages/eslint-plugin/src/rules/prefer-optional-chain-utils/analyzeChain.ts file. Could you please resolve it?

[auvred]

LGTM! Thanks for working on this 🚀

[JoshuaKGoldberg]

LGTM!

Since @bradzacher touched a ton of this stuff in #6397, will wait for a bit in case Brad has time to review.