After 2.0.20 dropped today I'm getting a strange error when loading with this mod enabled:

Failed to load mods: Cannot serialise ttype=function

This is the only mod it wants to disable because of that, and disabling it makes loading succeed; but looking at the code here I have no idea what's causing that error.

Okay, so apparently,

data.raw.tile['ice-smooth'].collision_mask = tile_collision_masks.ground

is the problem.... tile_collision_masks.ground is a function now...?

Yeah, the code now looks like this in base/prototypes/tile/tile-collision-masks.lua

tile_collision_masks.ground = function()
  return
  {layers={
    ground_tile=true
  }}
end

so thats fun. just need to add () on those two lines then

Hmm seems like it was a change in the 2.0.18 experimental version. I'll have an update available soon.