fix crash when closing the application

Change-Id: I87bb9bcc3a3c4951a8d60d24203d9e4b3cff02a7

mainwindow.cpp

@@ -290,6 +290,7 @@ MainWindow::closeEvent(QCloseEvent* event)
         settings.setValue(SettingsKey::geometry, saveGeometry());
         settings.setValue(SettingsKey::windowState, saveState());
     }
+    this->disconnect(screenChangedConnection_);
     LRCInstance::reset();
     QMainWindow::closeEvent(event);
 }

smartlistmodel.cpp

@@ -40,9 +40,7 @@ SmartListModel::SmartListModel(const lrc::api::account::Info &acc, QObject *pare
 int SmartListModel::rowCount(const QModelIndex &parent) const
 {
     if (!parent.isValid()) {
-        try {
-            return acc_.conversationModel->allFilteredConversations().size();
-        } catch (...) {}
+        return acc_.conversationModel->allFilteredConversations().size();
     }
     return 0; // A valid QModelIndex returns 0 as no entry has sub-elements
 }