Possible bug: executor_entities_collection.hpp::update_entities

Bug report

https://github.com/ros2/rclcpp/blob/a78d0cbd33b8fe0b4db25c04f7e10017bfca6061/rclcpp/include/rclcpp/executors/executor_entities_collection.hpp#L75-L82

I am confused about the

if (entity) {

in line 78. Would this not lead to the on_removed callback not being called, in race cases, even though the element was removed ?
@wjwwood @mjcarroll Is this intended, or a bug ?

Obviously, it's kind of useless, to call the callback with a nullptr, but the behavior is still strange to me. I ran into this issue, as internal structures of my code were not cleaned up, due to the callback not being called.