### 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)

if (!editor_property_map.has(p_prop)) {
		return;
	}
	for (EditorProperty *E : editor_property_map[p_prop]) {
		E->update_property();
		E->update_editor_property_status();
		E->update_cache();
	}
}
void EditorInspector::_clear() {
	while (main_vbox->get_child_count()) {
		memdelete(main_vbox->get_child(0));
	}
	property_selected = StringName();
	property_focusable = -1;
	editor_property_map.clear();
	sections.clear();
	pending.clear();
	restart_request_props.clear();
	if (_is_main_editor_inspector()) {
		EditorNode::get_singleton()->hide_unused_editors(this);
	}
}
Object *EditorInspector::get_edited_object() {