Here is the log from a freshly restarted server... All I did here was start the server, join then try to type in the chat and this is the error:
https://pastebin.com/MkjyWsqA

Here is the log file from before I restarted:
2021-07-02-1.log

Not sure what is going on here. To my knowledge, there aren't any turtles placed or running.

Duplicate of #96
This issue is fixed in 0.6.7b