The PVE community of this game is actually pretty good TC, save for a few rotten apples, unlucky your child came across one, if she wants to continue playing you ought to tell her this can happen occasionally and that she shouldn't get frustrated over it because it lacks any importance whatsoever.

Piece of advice too if she's a little sensitive, you might want her to stay away from any PVP mode, including the one from this game. They are sewers. Always. No exception.