Help with unknown error: `filePath` should be an absolute path, but got `eslint.config.mjs`

[SeawardSalmon6]

Environment

Node version: v20.18.2
npm version: 10.8.2
Local ESLint version: 9.22.0
Global ESLint version: None
Operating System: Windows 11 / WSL 2

What parser are you using?

@typescript-eslint/parser

What did you do?

I was trying to run the config inspector in my project. It was originally written with .eslintrc.json from the old config and some weeks ago we bumped our ESLint to the latest version. We ran the compat tool from ESLint to update our config files to the new flat config format but for some reason I couldn't find out I can't get to use config inspector because of the error below.

Configuration

Our current eslint.config.mjs is the following:

import { fixupConfigRules, fixupPluginRules } from '@eslint/compat';
import { FlatCompat } from '@eslint/eslintrc';
import js from '@eslint/js';
import typescriptEslint from '@typescript-eslint/eslint-plugin';
import tsParser from '@typescript-eslint/parser';
import vitest from '@vitest/eslint-plugin';
import _import from 'eslint-plugin-import';
import importHelpers from 'eslint-plugin-import-helpers';
import prettier from 'eslint-plugin-prettier';
import react from 'eslint-plugin-react';
import reactRefresh from 'eslint-plugin-react-refresh';
import globals from 'globals';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
const compat = new FlatCompat({
  baseDirectory: __dirname,
  recommendedConfig: js.configs.recommended,
  allConfig: js.configs.all,
});

/** @type { import("eslint").Linter.Config[] } */
export default [
  {
    ignores: [
      '**/node_modules/',
      '**/dist/',
      '**/build/',
      '**/public/',
      '**/.eslintcache',
      '**/tsconfig.tsbuildinfo',
    ],
  },
  ...fixupConfigRules(
    compat.extends(
      'eslint:recommended',
      'plugin:@typescript-eslint/strict',
      'plugin:@typescript-eslint/stylistic',
      'plugin:import/recommended',
      'plugin:import/typescript',
      'plugin:react/recommended',
      'plugin:react-hooks/recommended',
      'plugin:react/jsx-runtime',
      'plugin:prettier/recommended',
    ),
  ),
  {
    plugins: {
      react: fixupPluginRules(react),
      prettier: fixupPluginRules(prettier),
      'react-refresh': reactRefresh,
      'import-helpers': importHelpers,
      import: fixupPluginRules(_import),
      '@vitest': vitest,
      '@typescript-eslint': fixupPluginRules(typescriptEslint),
    },

    languageOptions: {
      ...react.configs.recommended.languageOptions,

      globals: {
        ...globals.browser,
        ...globals.serviceworker,
      },

      parser: tsParser,
      ecmaVersion: 'latest',
      sourceType: 'module',

      parserOptions: {
        ecmaFeatures: {
          jsx: true,
        },

        project: './tsconfig.eslint.json',
      },
    },

    settings: {
      react: {
        version: 'detect',
      },

      'import/resolver': {
        alias: {
          map: [
            ['~', './src/'],
            ['~apis', './src/apis/'],
            ['~components', './src/components/'],
            ['~contexts', './src/contexts/'],
            ['~hooks', './src/hooks/'],
            ['~icons', './src/icons/'],
            ['~pages', './src/pages/'],
            ['~services', './src/services/'],
            ['~styles', './src/sass/'],
            ['~utils', './src/utils/'],
            ['~types', './src/types/'],
            ['~constants', './src/constants/'],
          ],

          extensions: ['.ts', '.tsx', '.js', '.jsx', '.json', '.scss', '.css'],
        },
      },
    },

    rules: <projectRules>,
  },
];

Stack trace

Failed to load `eslint.config.js`.
Note that `@eslint/config-inspector` only works with the flat config format:
https://eslint.org/docs/latest/use/configure/configuration-files-new
Error: 'filePath' should be an absolute path, but got eslint.config.mjs.
    at OverrideTester.test (file:///home/salmon/icount/ic-admin/node_modules/@eslint/eslintrc/lib/config-array/override-tester.js:191:19)
    at flatConfig.files (file:///home/salmon/icount/ic-admin/node_modules/@eslint/eslintrc/lib/flat-compat.js:122:73)
    at match (file:///home/salmon/.npm/_npx/fadb285f08a830ab/node_modules/@eslint/config-inspector/dist/cli.mjs:5377:11)
    at file:///home/salmon/.npm/_npx/fadb285f08a830ab/node_modules/@eslint/config-inspector/dist/cli.mjs:5389:10
    at Array.some (<anonymous>)
    at pathMatches (file:///home/salmon/.npm/_npx/fadb285f08a830ab/node_modules/@eslint/config-inspector/dist/cli.mjs:5384:44)
    at file:///home/salmon/.npm/_npx/fadb285f08a830ab/node_modules/@eslint/config-inspector/dist/cli.mjs:5924:8
    at ConfigArray.forEach (<anonymous>)
    at ConfigArray.getConfigWithStatus (file:///home/salmon/.npm/_npx/fadb285f08a830ab/node_modules/@eslint/config-inspector/dist/cli.mjs:5850:8)
    at matchFile (file:///home/salmon/.npm/_npx/fadb285f08a830ab/node_modules/@eslint/config-inspector/dist/cli.mjs:8097:43)

[Lippiece]

Try to comment your used configs and plugins to pinpoint what breaks. It seems hardcore uses some of the culprits, for example, and astro/recommended also has this issue.

Come to think of it, old astro config has this issue. Current hardcore also requires compat, so it's most probably because of inspector not supporting old formats.

[rgilsimoes]

I found out that it was @typescript-eslint/recommended in my case, causing this issue.

[MarcosBustamante]

@rgilsimoes how did you fix the problem?