### 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)

emit_signal("page_changed", max_page);
}
void EditorPaginator::update(int p_page, int p_max_page) {
	page = p_page;
	max_page = p_max_page;
	
	first_page_button->set_disabled(page == 0);
	prev_page_button->set_disabled(page == 0);
	next_page_button->set_disabled(page == max_page);
	last_page_button->set_disabled(page == max_page);
	
	page_line_edit->set_text(vformat("%d", page + 1));
	page_count_label->set_text(vformat("/ %d", max_page + 1));
}
void EditorPaginator::_notification(int p_what) {
	switch (p_what) {
		case NOTIFICATION_ENTER_TREE:
		case NOTIFICATION_THEME_CHANGED: {
			first_page_button->set_icon(get_theme_icon(SNAME("PageFirst"), SNAME("EditorIcons")));
			prev_page_button->set_icon(get_theme_icon(SNAME("PagePrevious"), SNAME("EditorIcons")));
			next_page_button->set_icon(get_theme_icon(SNAME("PageNext"), SNAME("EditorIcons")));
			last_page_button->set_icon(get_theme_icon(SNAME("PageLast"), SNAME("EditorIcons")));
		} break;
	}
}
void EditorPaginator::_bind_methods() {
	ADD_SIGNAL(MethodInfo("page_changed", PropertyInfo(Variant::INT, "page")));
}
EditorPaginator::EditorPaginator() {