title: Customize error message in yii2 REST API
body: <p>I want to customize this following error message</p>
  
  <pre><code>Error 404: Not Found
  {
      "name": "Not Found",
      "message": "Object not found: 6",
      "code": 0,
      "status": 404,
      "type": "yii\\web\\NotFoundHttpException"
  }
  </code></pre>
  
  <p>to:</p>
  
  <pre><code>Error 404: Not Found
  {
      "name": "Not Found",
      "message": "Country not found for: 6",
      "code": 404,
      "status": Error
  }
  </code></pre>
  
  <p>Where is need to write this customization code?</p>