LibGUI: Make GUI::SettingsWindow::add_tab() return ErrorOr

This allows us to use TRY() when creating settings UI.

Userland/Applications/BrowserSettings/main.cpp

@@ -26,7 +26,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto window = TRY(GUI::SettingsWindow::try_create("Browser Settings", GUI::SettingsWindow::ShowDefaultsButton::Yes));
     window->set_icon(app_icon.bitmap_for_size(16));
-    window->add_tab<BrowserSettingsWidget>("Browser");
+    TRY(window->add_tab<BrowserSettingsWidget>("Browser"));
 
     window->show();
     return app->exec();

Userland/Applications/DisplaySettings/main.cpp

@@ -27,10 +27,10 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto app_icon = GUI::Icon::default_icon("app-display-settings");
 
     auto window = TRY(GUI::SettingsWindow::try_create("Display Settings"));
-    window->add_tab<DisplaySettings::BackgroundSettingsWidget>("Background");
-    window->add_tab<DisplaySettings::FontSettingsWidget>("Fonts");
-    window->add_tab<DisplaySettings::MonitorSettingsWidget>("Monitor");
-    window->add_tab<DisplaySettings::DesktopSettingsWidget>("Workspaces");
+    TRY(window->add_tab<DisplaySettings::BackgroundSettingsWidget>("Background"));
+    TRY(window->add_tab<DisplaySettings::FontSettingsWidget>("Fonts"));
+    TRY(window->add_tab<DisplaySettings::MonitorSettingsWidget>("Monitor"));
+    TRY(window->add_tab<DisplaySettings::DesktopSettingsWidget>("Workspaces"));
 
     window->set_icon(app_icon.bitmap_for_size(16));
 

Userland/Applications/KeyboardSettings/main.cpp

@@ -31,7 +31,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto window = TRY(GUI::SettingsWindow::try_create("Keyboard Settings"));
     window->set_icon(app_icon.bitmap_for_size(16));
-    window->add_tab<KeyboardSettingsWidget>("Keyboard");
+    TRY(window->add_tab<KeyboardSettingsWidget>("Keyboard"));
 
     window->show();
     return app->exec();

Userland/Applications/MailSettings/main.cpp

@@ -28,7 +28,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto app_icon = GUI::Icon::default_icon("app-mail");
 
     auto window = GUI::SettingsWindow::construct("Mail Settings", GUI::SettingsWindow::ShowDefaultsButton::Yes);
-    window->add_tab<MailSettingsWidget>("Mail");
+    TRY(window->add_tab<MailSettingsWidget>("Mail"));
     window->set_icon(app_icon.bitmap_for_size(16));
 
     window->show();

Userland/Applications/MouseSettings/main.cpp

@@ -26,8 +26,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto app_icon = GUI::Icon::default_icon("app-mouse");
 
     auto window = TRY(GUI::SettingsWindow::try_create("Mouse Settings", GUI::SettingsWindow::ShowDefaultsButton::Yes));
-    window->add_tab<MouseWidget>("Mouse");
-    window->add_tab<ThemeWidget>("Cursor Theme");
+    TRY(window->add_tab<MouseWidget>("Mouse"));
+    TRY(window->add_tab<ThemeWidget>("Cursor Theme"));
     window->set_icon(app_icon.bitmap_for_size(16));
 
     window->show();

Userland/Applications/TerminalSettings/main.cpp

@@ -28,8 +28,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto window = TRY(GUI::SettingsWindow::try_create("Terminal Settings"));
     window->set_icon(app_icon.bitmap_for_size(16));
-    window->add_tab<TerminalSettingsMainWidget>("Terminal");
-    window->add_tab<TerminalSettingsViewWidget>("View");
+    TRY(window->add_tab<TerminalSettingsMainWidget>("Terminal"));
+    TRY(window->add_tab<TerminalSettingsViewWidget>("View"));
 
     window->show();
     return app->exec();

Userland/Libraries/LibGUI/SettingsWindow.h

@@ -32,11 +32,11 @@ public:
     virtual ~SettingsWindow() override;
 
     template<class T, class... Args>
-    T& add_tab(StringView const& title, Args&&... args)
+    ErrorOr<NonnullRefPtr<T>> add_tab(String title, Args&&... args)
     {
-        auto& t = m_tab_widget->add_tab<T>(title, forward<Args>(args)...);
-        m_tabs.append(t);
-        return t;
+        auto tab = TRY(m_tab_widget->try_add_tab<T>(move(title), forward<Args>(args)...));
+        TRY(m_tabs.try_append(tab));
+        return tab;
     }
 
 private: