Hello,
Similar to Thalius, I've also found issues running this in 1.16. I can load a world perfectly fine, but breaking a rock block and triggering a cave-in causes a divide by zero exception:
System.DivideByZeroException: Attempted to divide by zero.
at Vintagestory.GameContent.POIRegistry.GetNearestPoi(Vec3d centerPos, Single radius, PoiMatcher matcher)
at ChaosLands.BlockBehaviorCaveIn.OnBlockBroken(IWorldAccessor world, BlockPos pos, IPlayer byPlayer, EnumHandling& handling)
Here's the full crash log:
https://pastebin.com/cmdcqW6n
Although I've just remembered a cave-in happened once before, so maybe it's a problem with my game...