### Godot version

v4.0.beta17.mono.official [c40020513]

### System information

Window 11, Forward+, GTX 1060

### Issue description

Adding two theme variations in a row result to a  crash.

https://user-images.githubusercontent.com/93253123/217037249-1ce1d56d-beb6-4435-83ad-9f8a07fe0e96.mp4



### Steps to reproduce

1. Create a project.
2. Create a theme.
3. Double click to go in the theme editor.
4. Click on manage items buttons.
5. In the add type field type a name to add a type.
6. type another name to add a second type.
7. Crash.

### Minimal reproduction project

[ThemeVariationCrash.zip](https://github.com/godotengine/godot/files/10665863/ThemeVariationCrash.zip)

return object;
}
void EditorInspector::edit(Object *p_object) {
	if (object == p_object) {
		return;
	}
	if (object) {
		_clear();
		object->disconnect("property_list_changed", callable_mp(this, &EditorInspector::_changed_callback));
	}
	per_array_page.clear();
	object = p_object;
	if (object) {
		update_scroll_request = 0; 
		if (scroll_cache.has(object->get_instance_id())) { 
			update_scroll_request = scroll_cache[object->get_instance_id()]; 
		}
		object->connect("property_list_changed", callable_mp(this, &EditorInspector::_changed_callback));
		update_tree();
	}
	emit_signal(SNAME("edited_object_changed"));
}
void EditorInspector::set_keying(bool p_active) {