I've had this problem twice now, whenever you go into trial chambers and start fighting, after 2 to 5 minutes randomly  an net.minecraft.ReportedException: Exception ticking world will occur.

After this happening 3 or 4 times then a net.minecraft.ReportedException: Ticking entity will repeteadly stop the server.

I have attached both crash reports. This has happened in different trial chambers, to solve it I had to tp myself out of it.

If I load the chunks after the 2nd exception happened server would go down inmeadiately..