### 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
if (p_custom_action_name == "select_current") {
		Node *scene = editor_data.get_edited_scene_root();
		if (!scene) {
			show_accept(TTR("There is no defined scene to run."), TTR("OK"));
			return;
		}
		pick_main_scene->hide();
		if (!FileAccess::exists(scene->get_scene_file_path())) {
			current_menu_option = FILE_SAVE_AND_RUN_MAIN_SCENE;
			_menu_option_confirm(FILE_SAVE_AS_SCENE, true);
			file->set_title(TTR("Save scene before running..."));
		} else {
			current_menu_option = SETTINGS_PICK_MAIN_SCENE;
			_dialog_action(scene->get_scene_file_path());
		}
	}
}
Ref<Texture2D> EditorNode::_get_class_or_script_icon(const String &p_class, const Ref<Script> &p_script, const String &p_fallback) {