### 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 true;
				}
			}
		}
	} else {
		
		if (FileAccess::exists(path + ".import")) {
			return true;
		}
	}
	return false;
}
void EditorNode::request_instantiate_scene(const String &p_path) {
	SceneTreeDock::get_singleton()->instantiate(p_path);
}
void EditorNode::request_instantiate_scenes(const Vector<String> &p_files) {
	SceneTreeDock::get_singleton()->instantiate_scenes(p_files);
}
void EditorNode::_inherit_request(String p_file) {
	current_menu_option = FILE_NEW_INHERITED_SCENE;
	_dialog_action(p_file);
}
void EditorNode::_instantiate_request(const Vector<String> &p_files) {
	request_instantiate_scenes(p_files);
}
void EditorNode::_close_messages() {
	old_split_ofs = center_split->get_split_offset();
	center_split->set_split_offset(0);
}
void EditorNode::_show_messages() {