### 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)

}
	
	{
		for (int i = icon_items_list->get_child_count() - 1; i >= 0; i--) {
			Node *node = icon_items_list->get_child(i);
			node->queue_free();
			icon_items_list->remove_child(node);
		}
		HashMap<StringName, bool> icon_items = _get_type_items(edited_type, &Theme::get_icon_list, show_default);
		for (const KeyValue<StringName, bool> &E : icon_items) {
			HBoxContainer *item_control = _create_property_control(Theme::DATA_TYPE_ICON, E.key, E.value);
			EditorResourcePicker *item_editor = memnew(EditorResourcePicker);
			item_editor->set_h_size_flags(SIZE_EXPAND_FILL);
			item_editor->set_base_type("Texture2D");
			item_control->add_child(item_editor);
			if (E.value) {
				if (edited_theme->has_icon(E.key, edited_type)) {
					item_editor->set_edited_resource(edited_theme->get_icon(E.key, edited_type));
				} else {
					item_editor->set_edited_resource(Ref<Resource>());
				}
				item_editor->connect("resource_selected", callable_mp(this, &ThemeTypeEditor::_edit_resource_item));
				item_editor->connect("resource_changed", callable_mp(this, &ThemeTypeEditor::_icon_item_changed).bind(E.key));
			} else {
				if (ThemeDB::get_singleton()->get_default_theme()->has_icon(E.key, edited_type)) {
					item_editor->set_edited_resource(ThemeDB::get_singleton()->get_default_theme()->get_icon(E.key, edited_type));
				} else {
					item_editor->set_edited_resource(Ref<Resource>());
				}
				item_editor->set_editable(false);