code: public com.google.rpc.Status getError() {
      if (resultCase_ == 4) {
         return (com.google.rpc.Status) result_;
      }
      return com.google.rpc.Status.getDefaultInstance();
    }
docs: <pre>
  The error result of the operation in case of failure or cancellation.
  </pre>
  
  <code>.google.rpc.Status error = 4;</code>