After loading in the world the game sort of half-crashes The game stays open, but the backgrounds bug out and the game needs to be shut down with the task manager. Looking back over the logs, it says that it happened during feature placement and really starts breaking down because of an "Invalid block entity betterarcheology:sus_block".
I'm using a bunch of other mods, for optimization, so I'm chalking up the limbo crash state to them trying to salvage it.

It doesn't happen immediately though. you can even log out normally before anything goes wrong. Though one oddity is that when relogging the first few times, it duplicated the bonus chest, so I'm guessing something bugged out in feature placement after the bonus chest, but before the game thought it was done with feature placement, so it did it again.

Here's a link to a copy of the logs VV
https://mclo.gs/cxeRNxS