Hanging hardware goes on first

I was finishing a painting the other day, and put the hanging hardware on the back. I always do this before I start a painting, but this time I didn't. Anyway, while screwing in a hanger, the screw driver slipped and rammed into the wood panel. Yes, on the other side the layer of ply had broken. Luckily, I can fix it. After the paint dries, cut out the wood sticking out and put some hard sandable gesso on, then wet sand it. Also fortunate that the damaged part of the painting is not an extremely detailed part that would be hard to recreate.

Still, I was fit to be tied. But once I knew I could fix it, it was alright. Even had I painted over the damaged part, chances are that I would be the only one who knew or noticed anything wrong. But I cannot bear the thought of selling a painting with any type of damage to it.