Preview error handle.2

src/device/DeviceManager.cpp

@@ -179,6 +179,10 @@ void DeviceManager::initDevice() {
 				TRIGGER_EVENT(GUIEvents::ResponsePreviewData, nullptr, (QObject*)(&bytes));
 				qDebug() << "Preview data response event end!";
 			}
+			else{
+                previewing = false;
+			    QThread::sleep(3);
+			}
 			QThread::msleep(100);
 		}
 		});