while improving my demo I had mysterious crashs because of the following:
I added some SceneNodes and attached them to a DeleteAnimator, to make them disapperar after some time.
Later I checked collisions, and I tested which SceneNodee I did not hit.
That was a bad idea because I did not know which SceneNodes there still were,
and if I accidentally hit a scene node which was going to be deleted, I was in trouble.
It took some time to sort out this problem
So you better check which SceneNodes were hit, this is easier to handle.