### Godot version

4.1 beta2

### System information

Windows 10 Home

### Issue description

I had a control with a custom theme which i removed. When loading the project again the Theme Editor is opened and some actions, like Show Default or Override All, cause the editor to crash.

### Steps to reproduce

1. create a scene with a Control node
2. add a custom theme to it
3. click the theme so the Theme Editor opens
4. remove the theme
5. save the scene
6. close the project and open it again (Theme Editor needs to be opened when closing the project)
7. click Show Default or Override All

### Minimal reproduction project

[Godot41_themeEditorCrash.zip](https://github.com/godotengine/godot/files/11760454/Godot41_themeEditorCrash.zip)

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() {