I don't know what happened to item_sounds between .15 and .20 but a handful of mods have had this problem.
Failed to load mods: Voidcraft/prototypes/vanilla.lua:17: attempt to index global 'item_sounds' (a nil value)
stack traceback:
Voidcraft/prototypes/vanilla.lua:17: in main chunk
[C]: in function 'require'
Voidcraft/data.lua:3: in main chunk
