### Godot version

4.1 rc3

### System information

Windows 10.0.19045 - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1060 (NVIDIA; 30.0.15.1403) - Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz (8 Threads)

### Issue description

This™
![image](https://github.com/godotengine/godot/assets/2223172/cb33110f-a5b0-400a-951f-3fa425f05714)

It can still happen, but it's more difficult to trigger.

### Steps to reproduce

1. Create a new scene with a Control node
2. Add Theme to the Control
3. Open Theme Editor
4. Clear the `theme` property in Control
5. Save, with Theme Editor opened
6. Restart

### Minimal reproduction project

N/A
EditorFileDialog::set_default_display_mode((EditorFileDialog::DisplayMode)EDITOR_GET("filesystem/file_dialog/display_mode").operator int());
			bool theme_changed =
					EditorSettings::get_singleton()->check_changed_settings_in_group("interface/theme") ||
					EditorSettings::get_singleton()->check_changed_settings_in_group("interface/editor/font") ||
					EditorSettings::get_singleton()->check_changed_settings_in_group("interface/editor/main_font") ||
					EditorSettings::get_singleton()->check_changed_settings_in_group("interface/editor/code_font") ||
					EditorSettings::get_singleton()->check_changed_settings_in_group("text_editor/theme") ||
					EditorSettings::get_singleton()->check_changed_settings_in_group("text_editor/help/help") ||
					EditorSettings::get_singleton()->check_changed_settings_in_group("filesystem/file_dialog/thumbnail_size") ||
					EditorSettings::get_singleton()->check_changed_settings_in_group("run/output/font_size") ||
					EditorSettings::get_singleton()->check_changed_settings_in_group("interface/touchscreen/increase_scrollbar_touch_area") ||
					EditorSettings::get_singleton()->check_changed_settings_in_group("interface/touchscreen/scale_gizmo_handles");
			if (theme_changed) {
				theme = create_custom_theme(theme_base->get_theme());
				DisplayServer::set_early_window_clear_color_override(true, theme->get_color(SNAME("background"), SNAME("Editor")));
				theme_base->set_theme(theme);
				gui_base->set_theme(theme);
				get_window()->set_theme(theme);
				gui_base->add_theme_style_override("panel", gui_base->get_theme_stylebox(SNAME("Background"), SNAME("EditorStyles")));
				main_vbox->set_anchors_and_offsets_preset(Control::PRESET_FULL_RECT, Control::PRESET_MODE_MINSIZE, gui_base->get_theme_constant(SNAME("window_border_margin"), SNAME("Editor")));
				main_vbox->add_theme_constant_override("separation", gui_base->get_theme_constant(SNAME("top_bar_separation"), SNAME("Editor")));
				scene_root_parent->add_theme_style_override("panel", gui_base->get_theme_stylebox(SNAME("Content"), SNAME("EditorStyles")));
				bottom_panel->add_theme_style_override("panel", gui_base->get_theme_stylebox(SNAME("BottomPanel"), SNAME("EditorStyles")));
				tabbar_panel->add_theme_style_override("panel", gui_base->get_theme_stylebox(SNAME("tabbar_background"), SNAME("TabContainer")));
				scene_tabs->add_theme_constant_override("icon_max_width", gui_base->get_theme_constant(SNAME("class_icon_size"), SNAME("Editor")));
				scene_tab_add_ph->set_custom_minimum_size(scene_tab_add->get_minimum_size());
				main_menu->add_theme_style_override("hover", gui_base->get_theme_stylebox(SNAME("MenuHover"), SNAME("EditorStyles")));
			}
			scene_tabs->set_max_tab_width(int(EDITOR_GET("interface/scene_tabs/maximum_width")) * EDSCALE);
			_update_scene_tabs();