So at first I thought the mod was conflicting with Travelers Backpack, but after looking through the crash log it mentioned Polymorph and that seemed to the issue. I took out Polymorph and it loaded fine. I'm attaching the crash report in case it helps to fix the compatibility with Polymorph.
crash-2022-05-08_15.16.31-server.txt

Just update polymorph to one of the later versions - don't know in which one exactly it was fixed but you should really be looking for a new version when you get a crash like this.