[Adam]

Your partner didn't screw up, the shooter did. I've 'no-called' this before, and the catcalls are just as wild. Maybe he could have done something to prevent it, but he's new.
Did the shooter catch the ball with a toe on the line? Or did he catch it behind the line and then step on it?
Now, partner should have probably waved off the free throw as soon as the foot hit the line while the shooter had the ball. Then you wouldn't have had a made free throw to wave off.