Put configs under configs key

Author: NullVoxPopuli

lib/recommended.mjs

@@ -8,6 +8,7 @@ export const plugin = emberPlugin;
 export const parser = emberParser;
 
 export const base = {
+  files: ['**/*.{js,ts}'],
   plugins: { ember: emberPlugin },
   rules: {
     ...baseRules,
@@ -37,6 +38,9 @@ export const gts = {
   files: ['**/*.gts'],
   languageOptions: {
     parser: emberParser,
+    parserOptions: {
+      extraFileExtensions: ['.gts'],
+    },
     // parser options should be supplied in the consuming project
   },
   processor: 'ember/noop',
@@ -51,7 +55,9 @@ export default {
   plugin,
   parser,
   // Recommended config sets
-  base,
-  gjs,
-  gts,
+  configs: {
+    base,
+    gjs,
+    gts,
+  },
 };