We are still testing, i.e. wipes every now and then. The server was installed after update 1.27. We currently have several mods, we tried EDO weapons, Tactical FLAVA, currently SNAFU, but the problem was with every mod. After changing mods, there was always a wipe. The problem is most noticeable when the player logs out with a weapon in hand. After logging in, the server crashes with the error mentioned.

I'm adding mdmp files from server. I hope they help.

I added it above in the comment, but I'll add another one.

I looked at other logs and there's more. Both for vanilla weapons and modded weapons.

Same problem on my server. I am attaching the files. I'm desperate.