unregisterLight method
Implementation
void unregisterLight(ThermionEntity entity) async {
var children = await controller.getChildEntities(entity, true);
if (selected == entity || children.contains(selected)) {
selected = null;
controller.gizmo?.detach();
}
_lights.remove(entity);
_onUnloadController.add(entity);
_onUpdatedController.add(true);
}