mainwindow: wait till search is completed before launching new one

gui/mainwindow.cpp

@@ -157,6 +157,8 @@ void MainWindow::lineEditReturnPressed()
 	}
 	// TODO: validate q;
 	ui->lblSearchResults->setText("Searching...");
+	searchWatcher.cancel();
+	searchWatcher.waitForFinished();
 	QFuture<QVector<SearchResult>> searchFuture = QtConcurrent::run(
 		[&, q]()
 		{