Comment 8 for bug 899753

The problem is that glyphtracer does not handle large images correctly. There is some error in image scaling inside glyphtracer. This leads to crop_and_trace grabbing the wrong subimage which is sometimes empty/blank, which potrace then processes to return a PostScript file with no "moveto" command, which potrace_image then dies on because the "lines" list runs out of entries when looking for the first "moveto".

I'm a bit confused when looking at the code, so I am not sure where the actual bug is, but if you rescale your image down to 2000px or less, it should process correctly.