### 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 (c == bottom_editor) {
			continue;
		}
		Size2 minsize = c->get_combined_minimum_size();
		ms.width = MAX(ms.width, minsize.width);
		ms.height = MAX(ms.height, minsize.height);
	}
	if (keying) {
		Ref<Texture2D> key = get_theme_icon(SNAME("Key"), SNAME("EditorIcons"));
		ms.width += key->get_width() + get_theme_constant(SNAME("hseparator"), SNAME("Tree"));
	}
	if (deletable) {
		Ref<Texture2D> key = get_theme_icon(SNAME("Close"), SNAME("EditorIcons"));
		ms.width += key->get_width() + get_theme_constant(SNAME("hseparator"), SNAME("Tree"));
	}
	if (checkable) {
		Ref<Texture2D> check = get_theme_icon(SNAME("checked"), SNAME("CheckBox"));
		ms.width += check->get_width() + get_theme_constant(SNAME("h_separation"), SNAME("CheckBox")) + get_theme_constant(SNAME("hseparator"), SNAME("Tree"));
	}
	if (bottom_editor != nullptr && bottom_editor->is_visible()) {
		ms.height += get_theme_constant(SNAME("v_separation"));
		Size2 bems = bottom_editor->get_combined_minimum_size();
		
		ms.height += bems.height;
		ms.width = MAX(ms.width, bems.width);
	}
	return ms;
}
void EditorProperty::emit_changed(const StringName &p_property, const Variant &p_value, const StringName &p_field, bool p_changing) {