### 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
save_all_scenes();
	ProjectSettings::get_singleton()->save();
	disk_changed->hide();
}
void EditorNode::_reload_modified_scenes() {
	int current_idx = editor_data.get_edited_scene();
	for (int i = 0; i < editor_data.get_edited_scene_count(); i++) {
		if (editor_data.get_scene_path(i) == "") {
			continue;
		}
		uint64_t last_date = editor_data.get_scene_modified_time(i);
		uint64_t date = FileAccess::get_modified_time(editor_data.get_scene_path(i));
		if (date > last_date) {
			String filename = editor_data.get_scene_path(i);
			editor_data.set_edited_scene(i);
			_remove_edited_scene(false);
			Error err = load_scene(filename, false, false, true, false, true);
			if (err != OK) {
				ERR_PRINT(vformat("Failed to load scene: %s", filename));
			}
			editor_data.move_edited_scene_to_index(i);
		}
	}
	set_current_scene(current_idx);
	_update_scene_tabs();
	disk_changed->hide();
}
void EditorNode::_reload_project_settings() {