Environment

Node version: v18.10.0
npm version: v8.19.2
Local ESLint version: v8.25.0 (Currently used)
Global ESLint version: Not found
Operating System: darwin 21.6.0

What parser are you using?

Default (Espree)

What did you do?

I was running some unit tests for a custom formatter against the new flat config API, and I noticed that getRulesMetaForResults is now throwing a TypeError for results that contain messages without a ruleId.

I found this to be the case for parser errors, for messages about unused eslint-disable directives and for warnings about ignored files. There could be other cases, too - my tests are not exhaustive.

Example 1: Parser error

const { default: { FlatESLint } } = await import('eslint/use-at-your-own-risk');

const eslint = new FlatESLint({ overrideConfigFile: true });
const results = await eslint.lintText('syntax error');
eslint.getRulesMetaForResults(results); // throws TypeError

Example 2: Unused eslint-disable directive

const { default: { FlatESLint } } = await import('eslint/use-at-your-own-risk');

const eslint = new FlatESLint({ overrideConfigFile: true, reportUnusedDisableDirectives: 'warn' });
const results = await eslint.lintText('// eslint-disable-line');
eslint.getRulesMetaForResults(results); // throws TypeError

Example 3: Ignored file

const { default: { FlatESLint } } = await import('eslint/use-at-your-own-risk');

const eslint = new FlatESLint({ overrideConfigFile: true });
const results = await eslint.lintText('', { filePath: '/.ignored.js', warnIgnored: true });
eslint.getRulesMetaForResults(results); // throws TypeError

What did you expect to happen?

getRulesMetaForResults should run without errors.

What actually happened?

A TypeError was thrown (the same for all examples):

.../node_modules/eslint/lib/config/flat-config-helpers.js:22
    if (ruleId.includes("/")) {
               ^

TypeError: Cannot read properties of null (reading 'includes')
    at parseRuleId (...node_modules/eslint/lib/config/flat-config-helpers.js:22:16)
    at getRuleFromConfig (.../node_modules/eslint/lib/config/flat-config-helpers.js:52:38)
    at FlatESLint.getRulesMetaForResults (.../node_modules/eslint/lib/eslint/flat-eslint.js:703:30)
    at file://.../example.mjs:5:8

Participation

• I am willing to submit a pull request for this issue.

Additional comments

No response