Make a CJS formatter compatible with an ESM only chalk.

.eslintrc.js

@@ -16,7 +16,8 @@ module.exports = {
 	ignorePatterns: [
 		// The CKEditor 5 core DLL build is created from JavaScript files.
 		// ESLint should not process compiled TypeScript.
-		'src/*.js'
+		'src/*.js',
+		'**/*.d.ts'
 	],
 	rules: {
 		'ckeditor5-rules/ckeditor-imports': 'error',

package.json

@@ -178,7 +178,7 @@
   },
   "scripts": {
     "postinstall": "node ./scripts/postinstall.mjs",
-    "lint": "eslint --quiet \"**/*.{js,ts,mjs}\" --format ./scripts/eslint-formatter.cjs",
+    "lint": "eslint --quiet \"**/*.{js,ts,mjs,cjs}\" --format ./scripts/eslint-formatter.cjs",
     "stylelint": "stylelint --quiet --allow-empty-input \"packages/**/*.css\" \"docs/**/*.css\"",
     "test": "node --max_old_space_size=4096 node_modules/@ckeditor/ckeditor5-dev-tests/bin/testautomated.js",
     "manual": "node --max_old_space_size=8192 node_modules/@ckeditor/ckeditor5-dev-tests/bin/testmanual.js",

scripts/eslint-formatter.cjs

@@ -9,7 +9,6 @@
 
 // See: https://eslint.org/docs/user-guide/formatters/#stylish.
 const eslintStylishFormatter = require( 'eslint-formatter-stylish' );
-const chalk = require( 'chalk' );
 
 // eslint-disable-next-line max-len
 const CODE_STYLE_URL = 'https://ckeditor.com/docs/ckeditor5/latest/framework/contributing/code-style.html#ckeditor-5-custom-eslint-rules';
@@ -20,7 +19,7 @@ const CODE_STYLE_URL = 'https://ckeditor.com/docs/ckeditor5/latest/framework/con
  *
  * @param {Array} results
  */
-module.exports = results => {
+module.exports = async results => {
 	console.log( eslintStylishFormatter( results ) );
 
 	const hasCKEditorErrors = results.some( item => {
@@ -37,6 +36,8 @@ module.exports = results => {
 		return;
 	}
 
+	const { default: chalk } = await import( 'chalk' );
+
 	console.log( chalk.cyan( 'CKEditor 5 custom ESLint rules are described in the "Code style" guide in the documentation.' ) );
 	console.log( chalk.underline( CODE_STYLE_URL ) );
 	console.log( '' );