### Godot version

4.1 beta2

### System information

Windows 10 Home

### Issue description

I had a control with a custom theme which i removed. When loading the project again the Theme Editor is opened and some actions, like Show Default or Override All, cause the editor to crash.

### Steps to reproduce

1. create a scene with a Control node
2. add a custom theme to it
3. click the theme so the Theme Editor opens
4. remove the theme
5. save the scene
6. close the project and open it again (Theme Editor needs to be opened when closing the project)
7. click Show Default or Override All

### Minimal reproduction project

[Godot41_themeEditorCrash.zip](https://github.com/godotengine/godot/files/11760454/Godot41_themeEditorCrash.zip)

main_menu->add_child(settings_menu);
	ED_SHORTCUT_AND_COMMAND("editor/editor_settings", TTR("Editor Settings..."));
	ED_SHORTCUT_OVERRIDE("editor/editor_settings", "macos", KeyModifierMask::META + Key::COMMA);
	settings_menu->add_shortcut(ED_GET_SHORTCUT("editor/editor_settings"), SETTINGS_PREFERENCES);
	settings_menu->add_shortcut(ED_SHORTCUT("editor/command_palette", TTR("Command Palette..."), KeyModifierMask::CMD_OR_CTRL | KeyModifierMask::SHIFT | Key::P), HELP_COMMAND_PALETTE);
	settings_menu->add_separator();
	editor_layouts = memnew(PopupMenu);
	editor_layouts->set_name("Layouts");
	editor_layouts->set_auto_translate(false);
	settings_menu->add_child(editor_layouts);
	editor_layouts->connect("id_pressed", callable_mp(this, &EditorNode::_layout_menu_option));
	settings_menu->add_submenu_item(TTR("Editor Layout"), "Layouts");
	settings_menu->add_separator();
	ED_SHORTCUT_AND_COMMAND("editor/take_screenshot", TTR("Take Screenshot"), KeyModifierMask::CTRL | Key::F12);
	ED_SHORTCUT_OVERRIDE("editor/take_screenshot", "macos", KeyModifierMask::META | Key::F12);
	settings_menu->add_shortcut(ED_GET_SHORTCUT("editor/take_screenshot"), EDITOR_SCREENSHOT);
	settings_menu->set_item_tooltip(-1, TTR("Screenshots are stored in the Editor Data/Settings Folder."));
#ifndef ANDROID_ENABLED
	ED_SHORTCUT_AND_COMMAND("editor/fullscreen_mode", TTR("Toggle Fullscreen"), KeyModifierMask::SHIFT | Key::F11);
	ED_SHORTCUT_OVERRIDE("editor/fullscreen_mode", "macos", KeyModifierMask::META | KeyModifierMask::CTRL | Key::F);
	settings_menu->add_shortcut(ED_GET_SHORTCUT("editor/fullscreen_mode"), SETTINGS_TOGGLE_FULLSCREEN);
#endif
	settings_menu->add_separator();
#ifndef ANDROID_ENABLED
	if (OS::get_singleton()->get_data_path() == OS::get_singleton()->get_config_path()) {
		
		settings_menu->add_item(TTR("Open Editor Data/Settings Folder"), SETTINGS_EDITOR_DATA_FOLDER);
	} else {
		
		settings_menu->add_item(TTR("Open Editor Data Folder"), SETTINGS_EDITOR_DATA_FOLDER);