No one is 100% perfect all the time. We are all going to make mistakes in the natural course of the tasks we do. And sometimes those mistakes will lead to issues bigger than the mistake itself.
Mistakes are like that though. The most innocuous, innocent mistake can lead to cascading problems that impact a large group of people. Similarly, huge bone-headed mistakes may not actually impact anyone (the “no harm, no foul” concept).
The size of the mistake itself should be measured two-fold: 1) how big the mistake itself was and 2) the impact of the mistake. The first is important because big mistakes may be indicators of process or quality issues that will eventually hurt customers if not addressed. The second because the customer is sacred. Customers/users don’t care if the mistake is innocent and small because the impact to them is the same no matter what. They just see that something is broken.