In the newly released Fantastic Beasts: Crimes of Grindelwald movie, we find a scene where Professor Dumbledore sees Gellert Grindelwald in the Mirror of Erised. Now, this doesn't seem to make sense because in the Harry Potter and the Deathly Hallows book we find Professor Dumbledore had seen his sister back alive in the Mirror of Erised in Harry's first year.
Is this another mistake made by J.K. Rowling or is there any explanation for this?