Thumbnailing is broken not only for GIFs >>132 but for large JPEGs >>159 as well, and results in a "post created" message linking to a fileless post.

https://chan.sankakucomplex.com/post/show/32952593 5841x8000 (8.1 MB JPG)
https://chan.sankakucomplex.com/post/show/32952594 5841x8000 (7 MB JPG)