### 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)

draw_texture(key, Vector2(size.width - keying_rect.position.x - key->get_width(), keying_rect.position.y), color2);
				} else {
					draw_texture(key, keying_rect.position, color2);
				}
			} else {
				keying_rect = Rect2();
			}
			if (deletable) {
				Ref<Texture2D> close;
				close = get_theme_icon(SNAME("Close"), SNAME("EditorIcons"));
				ofs -= close->get_width() + get_theme_constant(SNAME("hseparator"), SNAME("Tree"));
				Color color2(1, 1, 1);
				if (delete_hover) {
					color2.r *= 1.2;
					color2.g *= 1.2;
					color2.b *= 1.2;
				}
				delete_rect = Rect2(ofs, ((size.height - close->get_height()) / 2), close->get_width(), close->get_height());
				if (rtl) {
					draw_texture(close, Vector2(size.width - delete_rect.position.x - close->get_width(), delete_rect.position.y), color2);
				} else {
					draw_texture(close, delete_rect.position, color2);
				}
			} else {
				delete_rect = Rect2();
			}
		} break;
	}
}
void EditorProperty::set_label(const String &p_label) {