### 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
case 5:
				EditorScale::set_scale(1.75);
				break;
			case 6:
				EditorScale::set_scale(2.0);
				break;
			default:
				EditorScale::set_scale(EDITOR_GET("interface/editor/custom_display_scale"));
				break;
		}
	}
	
	Window *w = Object::cast_to<Window>(SceneTree::get_singleton()->get_root());
	if (w) {
		w->set_min_size(Size2(1024, 600) * EDSCALE);
	}
	EditorFileDialog::set_default_show_hidden_files(EDITOR_GET("filesystem/file_dialog/show_hidden_files"));
	EditorFileDialog::set_default_display_mode((EditorFileDialog::DisplayMode)EDITOR_GET("filesystem/file_dialog/display_mode").operator int());
	int swap_cancel_ok = EDITOR_GET("interface/editor/accept_dialog_cancel_ok_buttons");
	if (swap_cancel_ok != 0) { 
		
		AcceptDialog::set_swap_cancel_ok(swap_cancel_ok == 2);
	}
	ResourceLoader::set_abort_on_missing_resources(false);
	ResourceLoader::set_error_notify_func(&EditorNode::add_io_error);
	ResourceLoader::set_dependency_error_notify_func(&EditorNode::_dependency_error_report);
	SceneState::set_instantiation_warning_notify_func([](const String &p_warning) {
		add_io_warning(p_warning);
		callable_mp(EditorInterface::get_singleton(), &EditorInterface::mark_scene_as_unsaved).call_deferred();
	});