slice-image argument parsing bug: "num_tiles: invalid int value: ..."

[ArniDagur]

The command slice-image --dir slices *.jpg 9 results in:

usage: slice-image [-d DIR] [-f FORMAT] [-h] [-v] image num_tiles
slice-image: error: argument num_tiles: invalid int value: '0012tQn.jpg'

I tried making a shell script to avoid using glob:

find $(pwd) -maxdepth 1 -type f -name '*.png' -o -name '*.jpg' |
while read filename; do
    slice-image --output slices/ $filename 9 +
done

But I still get the same error:

usage: slice-image [-d DIR] [-f FORMAT] [-h] [-v] image num_tiles
slice-image: error: argument num_tiles: invalid int value: '/home/arni/colorize/DeOldify/training_images/006HsNn.jpg'
usage: slice-image [-d DIR] [-f FORMAT] [-h] [-v] image num_tiles
slice-image: error: argument num_tiles: invalid int value: '/home/arni/colorize/DeOldify/training_images/022SLOl.jpg'
usage: slice-image [-d DIR] [-f FORMAT] [-h] [-v] image num_tiles
slice-image: error: argument num_tiles: invalid int value: '/home/arni/colorize/DeOldify/training_images/234UW9T.jpg'