fine tune painting vanish effect

also observed the following bug:

when a player is alone on the server, steals a painting + tries to
escape, the scoring scene doesn’t load. This however isn’t an issue, as
soon as multiple (2 or more) players participate. I kind of know, why
that happens and I would know, where to look for a fix, but as our game
is supposed to be played with multiple clients anyway, I don’t need to
fix that right now..