Bug: hermes-eslint: no-unused-vars crashes in Flow libdefs with class declarations

[reosarevok]

Environment

Node version: v20.13.0
npm version: v10.5.2
Local ESLint version: v9.10.0 (Currently used)
Operating System: linux 5.15.0-119-generic
hermes-eslint version: v0.23.1

What did you do?

See minimal example at https://github.com/reosarevok/eslint-no-unused-vars-bug

What did you expect to happen?

Trying eslint 9 (while upgrading from 8) on our flow-typed codebase (using hermes-eslint), I was expecting no new issues.

What actually happened?

Oops! Something went wrong! :(

ESLint: 9.10.0

TypeError: Cannot read properties of undefined (reading 'some')
Occurred while linting /home/reosarevok/musicbrainz-server/flow-typed/npm/jed_v1.x.x.js:1
Rule: "no-unused-vars"
    at collectUnusedVariables (/home/reosarevok/musicbrainz-server/node_modules/eslint/lib/rules/no-unused-vars.js:751:71)
    at collectUnusedVariables (/home/reosarevok/musicbrainz-server/node_modules/eslint/lib/rules/no-unused-vars.js:829:17)
    at Program:exit (/home/reosarevok/musicbrainz-server/node_modules/eslint/lib/rules/no-unused-vars.js:841:36)
    at ruleErrorHandler (/home/reosarevok/musicbrainz-server/node_modules/eslint/lib/linter/linter.js:1083:48)
    at /home/reosarevok/musicbrainz-server/node_modules/eslint/lib/linter/safe-emitter.js:45:58
    at Array.forEach (<anonymous>)
    at Object.emit (/home/reosarevok/musicbrainz-server/node_modules/eslint/lib/linter/safe-emitter.js:45:38)
    at NodeEventGenerator.applySelector (/home/reosarevok/musicbrainz-server/node_modules/eslint/lib/linter/node-event-generator.js:297:26)
    at NodeEventGenerator.applySelectors (/home/reosarevok/musicbrainz-server/node_modules/eslint/lib/linter/node-event-generator.js:326:22)
    at NodeEventGenerator.leaveNode (/home/reosarevok/musicbrainz-server/node_modules/eslint/lib/linter/node-event-generator.js:348:14)

The issue was apparently added with eslint/eslint@1c173dc in eslint, but I reported it there (as eslint/eslint#18876) and they think it might be effectively an issue in the parser (eslint/eslint#18876 (comment)) so reporting it here too.

Link to Minimal Reproducible Example

https://github.com/reosarevok/eslint-no-unused-vars-bug