If a Unity Editor session is stopped after an AnimationInstancing object has been loaded, but before any have called Start(), the first time AnimationInstancingMgr.Instance is called will be when the AnimationInstancing object is destroyed.
This results in the error message
Some objects were not cleaned up when closing the scene. (Did you spawn new GameObjects from OnDestroy?)
The following scene GameObjects were found:
(singleton) AnimationInstancing.AnimationInstancingMgr
If a Unity Editor session is stopped after an AnimationInstancing object has been loaded, but before any have called Start(), the first time AnimationInstancingMgr.Instance is called will be when the AnimationInstancing object is destroyed.
This results in the error message