Bug: Empty CSS file causes TypeError: Error while loading rule 'css/font-family-fallbacks': Cannot read properties of undefined (reading 'cssWideKeywords')

[nwcm]

Environment

ESLint version: ESLint: 9.39.4
@eslint/css version: @eslint/css@npm:1.3.0
Node version: v24.16.0
npm version: 11.13.0
Operating System: Windows 11

Which language are you using?

stylesheet

What did you do?

Configuration

empty css file causes exception

import css from "@eslint/css";

import { defineConfig } from "eslint/config";

export default defineConfig([

  {
    files: ["src/**/*.css"],
    plugins: { css },
    extends: ["css/recommended"]
  }
]);

{}

What did you expect to happen?

yarn eslint

What actually happened?

Oops! Something went wrong! :(

ESLint: 9.39.4

TypeError: Error while loading rule 'css/font-family-fallbacks': Cannot read properties of undefined (reading 'cssWideKeywords')
Occurred while linting C:\Users\somePath\src\someComponent\component.css
    at Object.create (file:///C:/Users/somePath/node_modules/@eslint/css/dist/rules/font-family-fallbacks.js:111:58)
    at createRuleListeners (C:\Users\somePath\node_modules\eslint\lib\linter\linter.js:1019:15)
    at C:\Users\somePath\node_modules\eslint\lib\linter\linter.js:1151:7
    at Array.forEach (<anonymous>)
    at runRules (C:\Users\somePath\node_modules\eslint\lib\linter\linter.js:1085:31)
    at #flatVerifyWithoutProcessors (C:\Users\somePath\node_modules\eslint\lib\linter\linter.js:2115:4)
    at Linter._verifyWithFlatConfigArrayAndWithoutProcessors (C:\Users\somePath\node_modules\eslint\lib\linter\linter.js:2203:43)
    at Linter._verifyWithFlatConfigArray (C:\Users\some\node_modules\eslint\lib\linter\linter.js:2306:15)
    at Linter.verify (C:\Users\somePath\node_modules\eslint\lib\linter\linter.js:1677:10)
    at Linter.verifyAndFix (C:\Users\somePath\node_modules\eslint\lib\linter\linter.js:2571:20)
    at verifyText (C:\Users\somePath\node_modules\eslint\lib\eslint\eslint-helpers.js:1180:45)
    at readAndVerifyFile (C:\Users\somePath\node_modules\eslint\lib\eslint\eslint-helpers.js:1321:10)```

### Link to Minimal Reproducible Example

https://domain

### Participation

- [x] I am willing to submit a pull request for this issue.

### AI acknowledgment

- [x] I did not use AI to generate this issue report.
- [ ] (If the above is not checked) I have reviewed the AI-generated content before submitting.

### Additional comments

_No response_

[fasttime]

Thanks for the report @nwcm. I can reproduce the issue. Would you like to submit a pull request with a fix?

[nwcm]

I won't have much time over the next week or so, but after that if it still remains I can give it a go

[Pixel998]

@nwcm Looks like you're missing language: "css/css" in your config.

[lumirlumir]

@nwcm Could you verify that adding language: "css/css" resolves your problem when you have a moment?