version: lithium-fabric-mc1.21-0.12.7
steps to re-create:

1. launch up a world with both lithium and betterchunkloading
2. move around, after a while, often a couple of seconds, game crashes.

https://gist.github.com/Mr-Squid42/252cd43da4d34c39b70da77feaec89e1

same issue for me as well

Can confirm.
Lithium 1.21-0.13.0
Fabric API 0.102.0
Fabric Loaded 0.16.0

From betterchunkloading's author : "better chunk loading is just adding a Ticket, while lithiums coremodding fails"

Unclear how this happens unless adding the ticket is done via an unusual path or the ticket is modified after being added

I'm having the same problem.
Minus Lithium, it works very well.

Issue still happens.

Issue still happens.

yep, still happens
crash-2024-09-25_19.02.30-server.txt

Workaround available here (needs to be tested/confirmed)
#571

Possible workaround is adding the line mixin.minimal_nonvanilla.world.expiring_chunk_tickets=false to the lithium.properties file