• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.
• I have read the FAQ and my problem is not listed.

Repro

{
  "rules": {
    "@typescript-eslint/prefer-optional-chain": "warn"
  }
}

// your repro code case
const a: { b: string | null } = { b: null };

const x = a.b && a.b?.includes('test');

Expected Result

The code is considered valid.

Actual Result

ESLint tells me Prefer using an optional chain expression instead, as it's more concise and easier to read..

Additional Info

Versions

In the above example the output of optional chaining would not be equivalent as a.b would short- circuit with a null value and return null. I'm sure this falls under the warning mentioned in the docs about edge cases but a nicer solution would be to either:

a. ignore optional chaining warnings for assignments only (using an option for the rule)
b. use type information (mentioned in #4820) to determine if the resulting value might be null