server crash report

https://pastebin.com/Hya8JfZq

I don't know what the players were doing when it happened and it appears to be one-off

https://pastebin.com/sbAy5KHB and https://pastebin.com/kLgduhCb seem to be the same issue. any hints on what could have caused this? my pack uses the newest version of the 1.12.2 foam fix as of this day FoamFix 0.10.8 (1.12.2) and apearantly setting :fixWorldEntityCleanup=true to false somehow fixes it but isnt that option important?

Seems like it's caused by a mod modifying the entity removal list when it shouldn't. Possibly in a network packet.