ci: Setup eslint-import-resolver-typescript for improved TS linting (#4996)

* Setup stricter linting for typescript

* make `import/no-unresolved` an error everywhere

* use prettier to format `.vscode/settings.default.json`

* address PR comments

packages/@n8n_io/eslint-config/base.js

@@ -2,12 +2,6 @@
  * @type {import('@types/eslint').ESLint.ConfigData}
  */
 const config = (module.exports = {
-	parser: '@typescript-eslint/parser',
-	parserOptions: {
-		sourceType: 'module',
-		project: ['./tsconfig.json'],
-	},
-
 	ignorePatterns: [
 		'node_modules/**',
 		'dist/**',
@@ -318,11 +312,21 @@ const config = (module.exports = {
 		//       eslint-plugin-import
 		// ----------------------------------
 
+		/**
+		 * https://github.com/import-js/eslint-plugin-import/blob/main/docs/rules/no-cycle.md
+		 */
+		'import/no-cycle': 'error',
+
 		/**
 		 * https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-default-export.md
 		 */
 		'import/no-default-export': 'error',
 
+		/**
+		 * https://github.com/import-js/eslint-plugin-import/blob/main/docs/rules/no-unresolved.md
+		 */
+		'import/no-unresolved': 'error',
+
 		/**
 		 * https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/order.md
 		 */

packages/@n8n_io/eslint-config/frontend.js

@@ -12,16 +12,6 @@ module.exports = {
 		node: true,
 	},
 
-	parser: 'vue-eslint-parser',
-	parserOptions: {
-		parser: {
-			ts: '@typescript-eslint/parser',
-			js: '@typescript-eslint/parser',
-			vue: 'vue-eslint-parser',
-			template: 'vue-eslint-parser',
-		},
-	},
-
 	ignorePatterns: ['**/*.js', '**/*.d.ts', 'vite.config.ts', '**/*.ts.snap'],
 
 	rules: {

packages/@n8n_io/eslint-config/package.json

@@ -10,6 +10,7 @@
     "eslint": "~8.28",
     "eslint-config-airbnb-typescript": "~17.0",
     "eslint-config-prettier": "~8.5",
+    "eslint-import-resolver-typescript": "~3.5",
     "eslint-plugin-diff": "~2.0",
     "eslint-plugin-import": "~2.26",
     "eslint-plugin-n8n-local-rules": "~1.0",

packages/@n8n_io/eslint-config/shared.js

@@ -0,0 +1,41 @@
+/**
+ * @type {(dir: string, mode: 'frontend' | undefined) => import('@types/eslint').ESLint.ConfigData}
+ */
+exports.sharedOptions = (tsconfigRootDir, mode) => {
+	const isFrontend = mode === 'frontend';
+	const parser = isFrontend ? 'vue-eslint-parser' : '@typescript-eslint/parser';
+	const extraParserOptions = isFrontend
+		? {
+				extraFileExtensions: ['.vue'],
+				parser: {
+					ts: '@typescript-eslint/parser',
+					js: '@typescript-eslint/parser',
+					vue: 'vue-eslint-parser',
+					template: 'vue-eslint-parser',
+				},
+		  }
+		: {};
+
+	const settings = {
+		'import/parsers': {
+			'@typescript-eslint/parser': isFrontend ? ['.ts', '.vue'] : ['.ts'],
+		},
+
+		'import/resolver': {
+			typescript: {
+				tsconfigRootDir,
+				project: './tsconfig.json',
+			},
+		},
+	};
+
+	return {
+		parser,
+		parserOptions: {
+			tsconfigRootDir,
+			project: ['./tsconfig.json'],
+			...extraParserOptions,
+		},
+		settings,
+	};
+};