Today I had a crash generating chunks on my server. I already opened an issue on Serene Seasons end but I think it might be related to ratlantis directly, as I can't really find it in the biome dictionary:

Glitchfiend/SereneSeasons#279

all issues regarding ratlantis are being closed as the dimension has been completely rewritten from the ground up and shouldnt have these issues anymore in 1.19 and beyond