public function handleRequestException(AphrontRequest $request, Exception $ex)
 {
     $viewer = $this->getViewer($request);
     $title = $ex->getExceptionTitle();
     $dialog = id(new AphrontDialogView())->setTitle($title)->setUser($viewer)->appendParagraph($ex->getMessage())->addCancelButton('/', pht('Proceed With Caution'));
     return id(new AphrontDialogResponse())->setDialog($dialog)->setHTTPResponseCode(500);
 }