chore: 🤖 re-enable mirage for core dummy app

Author: hashicc

addons/api/index.js

@@ -98,6 +98,6 @@ module.exports = {
   _includeMirageInBuild() {
     const env = this.parent.app?.env ?? 'production';
     const config = this.project.config(env);
-    return config.mirage.enabled || env !== 'production';
+    return config.mirage?.enabled || env !== 'production';
   },
 };

addons/core/tests/dummy/config/environment.js

@@ -41,6 +41,10 @@ module.exports = function (environment) {
       namespace: 'v1',
     },
 
+    mirage: {
+      enabled: true,
+    },
+
     enableConfirmService: false,
   };