Just throw and the test cases are designed to handle such a case by asserting that there is an error thrown. Then it is gonna re-hit / re-invoke your method with another valid input to assert that all went well. :) Take it easy, Make it simple..

HOW ON EARTH AM I SUPPOSED TO THROW AN ERROW AND CONTINUE THE DAMN CODE DUE TO KO RULE, HUH????

These color games this kata is doing is just driving me insane, I can't actually understand which one is black and which one is white. It is so unclear. And another thing that appears to me to be strange is : Why is black making the first move? Shouldn't it be white?