### 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)

ms.width += indent_depth * section_indent_size;
	}
	Ref<StyleBoxFlat> section_indent_style = get_theme_stylebox(SNAME("indent_box"), SNAME("EditorInspectorSection"));
	if (indent_depth > 0 && section_indent_style.is_valid()) {
		ms.width += section_indent_style->get_margin(SIDE_LEFT) + section_indent_style->get_margin(SIDE_RIGHT);
	}
	return ms;
}
void EditorInspectorSection::setup(const String &p_section, const String &p_label, Object *p_object, const Color &p_bg_color, bool p_foldable, int p_indent_depth) {
	section = p_section;
	label = p_label;
	object = p_object;
	bg_color = p_bg_color;
	foldable = p_foldable;
	indent_depth = p_indent_depth;
	if (!foldable && !vbox_added) {
		add_child(vbox);
		move_child(vbox, 0);
		vbox_added = true;
	}
	if (foldable) {
		_test_unfold();
		if (object->editor_is_section_unfolded(section)) {
			vbox->show();
		} else {
			vbox->hide();
		}
	}
}
void EditorInspectorSection::gui_input(const Ref<InputEvent> &p_event) {