If the throw goes into center field, but in your opinion the runner would've been safe at second with a good throw, you rule a sacrifice bunt and would only score an error if there is an advancement beyond second. What I mean is, the pitcher makes the turn to throw the runner out at second when he had no chance of retiring him. Good throw / bad throw, its a sacrifice (0-0), batter reached on the Fielder's Choice of retiring the runner at second. This is an old argument I don't really want to start again.
If instead you believe a good throw would've retired the runner at second (and he made a bad throw), or if there is a bobble on a come backer and everyone is safe where you REALLY believe the play at second would've been made, then its an E-1 and FC (0-1 on batter). In the later case, the ordinary effort play would be to go to first, so I would have to see the pitcher turning to second before the miss-play with lots of time to not credit the sacrifice, like he drops the ball transferring out of his glove. I'm going to score this one a sacrifice, reached first on E-1 (0-0 in the stats) almost all the time. If the pitcher boots the ball with his shoulders square to the plate (assume everyone safe), then its definitely Sacrifice (0-0), batter reaches on E-1.
Just my opinion....