This error hasn't been fixed for the Windows version (something about updating the camera rigth after getting the fire in the bonfire):
Please send this to the developers to help them resolve this issue:
ERR [string "code/game.lua"]:501: attempt to perform arithmetic on field 'xa' (a nil value)
Stack traceback:
[string "code/game.lua"]:141: in function <[string "code/game.lua"]:137>
[string "code/game.lua"]:501: in function 'update camera'