how to return a json Response when query_params with 'format=xlsx'

If there isn't a 'form' param in request ,I want return an error, but raised an error. 
```python
def list(self, request: Request, *args: Any, **kwargs: Any) -> Response:
    if self.request.query_params.get('form') and self.request.query_params.get('format') == 'xlsx':
        return Response({'error' : 'no form'})
```

error:

`Response data is a dict, not a DataFrame!`
