### 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
return export_as_menu;
}
void EditorNode::_global_menu_scene(const Variant &p_tag) {
	int idx = (int)p_tag;
	scene_tabs->set_current_tab(idx);
}
void EditorNode::_global_menu_new_window(const Variant &p_tag) {
	if (OS::get_singleton()->get_main_loop()) {
		List<String> args;
		args.push_back("-p");
		OS::get_singleton()->create_instance(args);
	}
}
void EditorNode::_dropped_files(const Vector<String> &p_files) {
	String to_path = ProjectSettings::get_singleton()->globalize_path(FileSystemDock::get_singleton()->get_current_directory());
	_add_dropped_files_recursive(p_files, to_path);
	EditorFileSystem::get_singleton()->scan_changes();
}
void EditorNode::_add_dropped_files_recursive(const Vector<String> &p_files, String to_path) {