This is also a very nice one!
The problem is that sometimes there could be a purple block (breakable wall) so even if you don't move, your "move" leads to a change in the level which could be a part of the solution.
We could add a pretty intricate check, like "if you didn't move and you didn't break anything, then it doesn't count as a move" but it is pretty complicated to implement and also even if it is frustrating, an error should count as an error unfortunately ahahah