As a temporary fix, I can confirm that adding something (Loathing Chat in this case) to the "Startup as Window" frame solves the problem in r9982, which crashes as described above with that frame is empty.
In testing the edits that I made (which were almost identical to yours, save that I called the boolean talon instead of vts) it failed every ~100 turns when birdform ended after the final slimed combat. Then when it went to re-slime and got the Welcome back adventure, it didn't use another gong...
This may be a bit of an obscure request, but is there any possibility an update could be made so that the script supports talon slash in birdform? It's a nice MP-cheap attack given a sufficiently buffed muscle, and obviously the feather are a nice little profit. Right now the script looks like...