HackStudio+LibGUI: Make fallible `TabWidget::add_tab()` non-fallible

Userland/DevTools/HackStudio/HackStudioWidget.cpp

@@ -1346,7 +1346,7 @@ ErrorOr<void> HackStudioWidget::create_action_tab(GUI::Widget& parent)
     m_todo_entries_widget = m_action_tab_widget->add_tab<ToDoEntriesWidget>("TODO"_string);
     m_terminal_wrapper = m_action_tab_widget->add_tab<TerminalWrapper>("Console"_string, false);
     auto debug_info_widget = TRY(DebugInfoWidget::create());
-    TRY(m_action_tab_widget->add_tab(debug_info_widget, "Debug"_string));
+    m_action_tab_widget->add_tab(debug_info_widget, "Debug"_string);
     m_debug_info_widget = debug_info_widget;
 
     m_debug_info_widget->on_backtrace_frame_selection = [this](Debug::DebugInfo::SourcePosition const& source_position) {

Userland/Libraries/LibGUI/TabWidget.h

@@ -64,11 +64,10 @@ public:
         return *t;
     }
 
-    ErrorOr<void> add_tab(NonnullRefPtr<Widget> const& tab, String title)
+    void add_tab(NonnullRefPtr<Widget> const& tab, String title)
     {
         tab->set_title(move(title));
-        TRY(try_add_widget(*tab));
-        return {};
+        add_widget(*tab);
     }
 
     void remove_tab(Widget& tab) { remove_widget(tab); }