World gen is very slow with negative sea level

When using the attached datapack with some custom world generation settings, generating the world is incredibly slow. Normally, my computer can generate a new world fairly quickly. However, something about this makes it stay at 0% for actual minutes. This may be a problem with what I've done in the datapack, but I'm also fairly sure that it's a weird custom world generation bug.

After letting it run for 10-ish minutes, it crashed with an IllegalArgumentException. I've also attached the crash report.

EDIT: Added an updated pack for 1.18.2 - the world still doesn't load, though.

EDIT 2: Added another updated pack for 1.19 snapshots - the world still doesn't load too.

UPDATE: After some testing, it's the negative sea level that's throwing Minecraft off.