Should have been an error and FC, but no mental error has been ruled a scored error in the last 3, maybe 4 decades. Unless you don't drop a ball or throw it away, the scorer has no beef with you in today's game. And in the OF even a drop is not certain to be an error if the player had to run more than a few steps. They really should stop scoring them at all. They are supposed to represent outs that should have been made, whether the ball is touched or not should not be relevant, but that is how is has evolved. I guess the scorers didn't want to take any heat from the players on anything that was too obvious to argue.