### 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)

fit_child_in_rect(c, Rect2(offset, size));
			}
		} break;
		case NOTIFICATION_DRAW: {
			int section_indent = 0;
			int section_indent_size = get_theme_constant(SNAME("indent_size"), SNAME("EditorInspectorSection"));
			if (indent_depth > 0 && section_indent_size > 0) {
				section_indent = 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()) {
				section_indent += section_indent_style->get_margin(SIDE_LEFT) + section_indent_style->get_margin(SIDE_RIGHT);
			}
			int header_width = get_size().width - section_indent;
			int header_offset_x = 0.0;
			bool rtl = is_layout_rtl();
			if (!rtl) {
				header_offset_x += section_indent;
			}
			
			int header_height = _get_header_height();
			Rect2 header_rect = Rect2(Vector2(header_offset_x, 0.0), Vector2(header_width, header_height));
			Color c = bg_color;
			c.a *= 0.4;
			if (foldable && header_rect.has_point(get_local_mouse_position())) {
				c = c.lightened(Input::get_singleton()->is_mouse_button_pressed(MouseButton::LEFT) ? -0.05 : 0.2);
			}
			draw_rect(header_rect, c);
			
			{