I think this crash is caused by snow layers?
crash-2020-07-27_18.54.26-server.txt

Setting double-slabs down is fine. When it snows (eg. using Serene Seasons), the doubled-slabs render with the "broken" texture pattern (purple/black chequers), and within seconds of loading a chunk containing said double slabs with snow the error linked above happens and the server crashes and dies completely. In a single-player setup the broken texture appears but there is no fatal crash afaik.

Ah, this was using MC 1.12.2 - it's in the log I think?

Sorry thanks :)

Should be fixed in the latest version :)