VIllager causes a crash with the message "Internal exception: java.lang.StackOverflowError."
Originally it took some time between the server re-launching and crashing like this, but when I teleported to the location of the villager stated in the crash report the server crashed instantly. Now the server crashes immediately after I join it. As such, the exact nature of what's causing the crash was impossible to determine.
I had a crash where a villager had a bed/job site/meeting point in their NBT data even after it was removed, this led to them crashing when they took ticking damage.