'Can't destroy Transform component' error when exiting play mode

[JohannesMP]

In 2018 and later (potentially 2017 as well, haven't tested) Unity has problems cleaning up the RuntimeDebugDraw object nested inside the hidden wrapper object when exiting play mode. For some reason it complains about something trying to delete its Transform component:

There is no call stack, so this is originating in Unity's own internal code.

[JohannesMP]

This issue appears to be resolved with changes in my pull request.

Since the RuntimeDebugDraw object only is destroyed like this when exiting play mode, it can be mitigated by unparenting it right as play mode exits, but before it is cleaned up. The object is still cleaned up correctly, just without an annoying error.