I return "0"

According to kata description:

You may assume the following:

If a and b are both numbers, neither of a or b will be 0.

but unfortunately, when I check my solution, appeared this error:

return (a % b) + (b % a)
ZeroDivisionError: integer division or modulo by zero

I did this kata in python.

I think that is sth wrong with test cases (for groovy):
assert Kata.game(3,2) == "Joe"
assert Kata.game(4,2) == "Mike"
assert Kata.game(9,1000) == "Joe"

When my code was testeted I've recieved the answer:
expected:<[45385593107843568]> but was:<[01011110001100111]>
Could sb explain me what is that ?

Maybe it's necessary to round temperature to 2 digits. Nobody measures temperature with 8-10 digits precision.

The same problem appears in java.