Two wrongs can make a right

One of my clients made a very foolish mistake.  I was somewhat upset, although philosophical, because the consequences weren’t as bad as they could have been.  I learned yesterday that the opposing party made an even bigger mistake that completed negated what my client had done.  In twenty years, it has never happened before that something stupid on my side got wiped out by something more stupid on the other side.  What could be better?