This seems to be related to generation as I can create a new world, fly around but after a while the game crashes, subsequent attempts to open that world will lead to the errors in the datapack message.
Please find my log attached here: https://gist.github.com/frog292j10/9bf9c2f90798154aa6a3b558fd006240
any ideas what mod/mods are causing this so I can remove them from my order? (I'm aware this is an abomination of a load order)
Thanks.