the response hasn't been received yet.
Download.getResponse
webkit.uriresponse.URIResponse getResponse()Retrieves the #WebKitURIResponse object that backs the download process.
Retrieves the #WebKitURIResponse object that backs the download process. This method returns null if called before the response is received from the server. You can connect to notify::response signal to be notified when the response is received.
Returns
the #WebKitURIResponse, or null if