Fixed crash when close main window.

application/mainwindow.cpp

@@ -133,6 +133,12 @@ void MainWindow::showEvent(QShowEvent *evt)
     }
 }
 
+void MainWindow::closeEvent(QCloseEvent *evt)
+{
+    Context::instance().destroy();
+    evt->accept();
+}
+
 void MainWindow::on_actionSettings_triggered()
 {
     SettingsForm *settings = new SettingsForm(this);

application/mainwindow.h

@@ -3,6 +3,7 @@
 
 #include <QMainWindow>
 #include <QLabel>
+#include <QCloseEvent>
 
 #include "logindialog.h"
 
@@ -40,6 +41,7 @@ private:
     // QWidget interface
 protected:
     void showEvent(QShowEvent *evt);
+    void closeEvent(QCloseEvent *evt) override;
 };
 
 #endif // MAINWINDOW_H