### 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
String current_renderer = GLOBAL_GET("rendering/renderer/rendering_method");
	PackedStringArray renderers = ProjectSettings::get_singleton()->get_custom_property_info().get(StringName("rendering/renderer/rendering_method")).hint_string.split(",", false);
	
	
	current_renderer = current_renderer.to_lower();
	for (int i = 0; i < renderers.size(); i++) {
		String rendering_method = renderers[i];
		
		if (rendering_method == "forward_plus") {
			renderer->add_item(TTR("Forward+"));
		}
		if (rendering_method == "mobile") {
			renderer->add_item(TTR("Mobile"));
		}
		if (rendering_method == "gl_compatibility") {
			renderer->add_item(TTR("Compatibility"));
		}
		renderer->set_item_metadata(i, rendering_method);
		
		rendering_method = rendering_method.to_lower();
		if (current_renderer == rendering_method) {
			renderer->select(i);
			renderer_current = i;
		}
	}
	_update_renderer_color();
	video_restart_dialog = memnew(ConfirmationDialog);
	video_restart_dialog->set_text(TTR("Changing the renderer requires restarting the editor."));
	video_restart_dialog->set_ok_button_text(TTR("Save & Restart"));
	video_restart_dialog->connect("confirmed", callable_mp(this, &EditorNode::_menu_option).bind(SET_RENDERER_NAME_SAVE_AND_RESTART));