My supervisor asks two questions when a mistake is made: “Did you do it on purpose?’ and “Can it be fixed?” If you answer “No” to the first, and “Yes” to the second, you have nothing to worry about.
(Of course, if you keep repeating the same mistake, that’s another story.)
It’s a refreshing change when I remember that I’ve worked in places when an employee is always guilty until proven innocent. I’ve even worked in places where an employee is always guilty, despite being proven innocent. I’ve even worked in places where an employee is always guilty – even before anything happens.
I learned this morning that I made a mistake the first time I did that side project for the other department. It was a rookie mistake, one I’m sure I’m not making now, that was in about 1% of the project. I learned how to fix it. It took less than an hour to fix, and I got on with my day.
(Ironically, this side project involves fixing other people’s errors.)