AssertionError: Sliced image shape does not equal the mask shape. This should never happen! If you see this issue, please report it as a bug!
fil = FilFinder2D(thresh, mask=thresh, distance= 100*u.pc)
fil.create_mask(border_masking=True, verbose=False, use_existing_mask=True)
fil.preprocess_image(flatten_percent=100)
fil.medskel(verbose=False)
fil.analyze_skeletons()