clean output buffer in case of thrown exception

Application/Controller/Admin/MailConfigCheck.php

@@ -100,6 +100,7 @@ class MailConfigCheck extends AdminDetailsController
             $this->addTplParam('mailer', $mail->getMailer());
             $this->addTplParam('communication', $communication);
         } catch (Exception $e) {
+            ob_end_clean();
             Registry::getUtilsView()->addErrorToDisplay($e);
         }
     }