Remove unused code and fix a warning

src/MainWindow.cpp

@@ -362,7 +362,7 @@ void MainWindow::init()
         // Connect tabCloseRequested for setting checked the appropiate menu entry.
         // Note these are called after the actual tab is closed only because they are connected
         // after connecting closeTab.
-        connect(ui->mainTab, &QTabWidget::tabCloseRequested, [=](int index) {
+        connect(ui->mainTab, &QTabWidget::tabCloseRequested, [=](int /*index*/) {
                 action->setChecked(ui->mainTab->indexOf(widget) != -1);
             });
     }

src/MainWindow.h

@@ -91,14 +91,6 @@ public:
     DBBrowserDB& getDb() { return db; }
     RemoteDatabase& getRemote() { return *m_remoteDb; }
 
-    enum Tabs
-    {
-        StructureTab,
-        BrowseTab,
-        PragmaTab,
-        ExecuteTab
-    };
-
 private:
     struct PragmaValues
     {