Version 1.3.0 and Ubuntu 19.04: (i DL game from itch.io page)
The file "mods/subterrane/defaults.lua" was only missing in my Github Repository, I've just added the file. Thank you for this. But in all itch.io downloads I can see this file. Sure you've not cloned my Github repository?
I used the non Github version from the itch.io download. you should reupload it again.