Lesson 2 - ImageCleaner error when idxs from_toplosses

I was getting an error when using ImageCleaner.
IndexError: index 1 is out of bounds for dimension 0 with size 1
I could find that idxs returned from by DatasetFormatter().from_toplosses(learn_cln) needs to have X+1 length for the dataset of length X in order for ImageCleaner to accept it. Simple .append(existing_index) solves this problem.
It was also noticed that DatasetFormatter().from_similars(learn_cln) returns the idxs x2 times longer than the actual dataset. It actually explains why this error did not pop-up when idxs is returned by DatasetFormatter().from_similars(learn_cln).
Does smb. else encounter this problem?