the radix argument handling should match the one defined for Number#toString if it is a counterpart
If radix is not present, let radixNumber be 10.
Else if radix is undefined, let radixNumber be 10.
Else, let radixNumber be ? ToInteger(radix).
If radixNumber < 2 or radixNumber > 36, throw a RangeError exception.
the radix argument handling should match the one defined for Number#toString if it is a counterpart