### 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)

checkable = p_checkable;
	queue_redraw();
	queue_sort();
}
bool EditorProperty::is_checkable() const {
	return checkable;
}
void EditorProperty::set_checked(bool p_checked) {
	checked = p_checked;
	queue_redraw();
}
bool EditorProperty::is_checked() const {
	return checked;
}
void EditorProperty::set_draw_warning(bool p_draw_warning) {
	draw_warning = p_draw_warning;
	queue_redraw();
}
void EditorProperty::set_keying(bool p_keying) {
	keying = p_keying;
	queue_redraw();
	queue_sort();
}
void EditorProperty::set_deletable(bool p_deletable) {