A bad outcome can happen without anyone having made a bad choice.

Bad things happen without anyone having erred. Illness, accidents, a project failing on factors nobody could see, all of it can arrive at the end of a chain of reasonable choices. The search for the mistake feels responsible and it is often just pain looking for a place to sit.

If you are combing through what happened for the moment you got it wrong, allow that the moment may not exist. Ask what you actually knew at the time. Where there was no way to know, there was no failure to find.