I'm getting the same issue, tried removing the line to see if that would at least let me load the mod, but upon loading the game again, i was given a similar error for a different line.
Seablock/data-updates.lua:680: attempt to index field 'hydrogen'(a nil value)
mods to be disabled:
seablock
I get the exact same error message. Tried everything I could, can't get Sea Block running. It's frustrating. Maybe one day running mods will be a bit more user friendly.