luajit: [string "R[1]=(R[1]+R[2])"]:1: attempt to perform arithmetic on a nil value
stack traceback:
        [string "R[1]=(R[1]+R[2])"]:1: in main chunk
        l.lua:35: in function '_'
        l.lua:39: in main chunk
        [C]: at 0x7ff6d90c2000