I've also had a problem with the PS to spine script! its been working since I've had the program, and suddenly it stopped. Now its asking me to save a PSD for every layer, not a PNG. I resaved the script with the one you linked to above and I get the same error. Any ideas?
I would like to mention that it SEEMS to only be an issue when I try to run this script on PS files that are smart objects that open to Illustrator, not smart objects made in PS. I don't remember this ever being an issue, but is it a known workaround? I just made a second file, rasterized all of the layers, and i had to drag them into a new file to wipe any lingering AI issues.