Humans often have expectations on things. Such expectations, however, are not always met, and mistakes can occur. It may be an unpleasant truth, but I believe we can reconcile with this reality.
What I define as a mistake (for the purposes of this text, at least) is this: a mistake is something that does not align with one's expectations and is deemed unpleasant. Mistakes depend what one's expectations are and if they, the mistakes, are unpleasant. The more specific one's expectations are, the more likely for certain details to be labelled as mistakes.
Suppose there is a sculptor. As he carves a statue, he holds specific expectations of what the statue will look like. When he finishes, he notices a detail: the nose is slightly curved. He did not expect the nose to look slightly curved and he finds the detail unpleasant, so he labels it a mistake. The statue has another detail that he did not expect: one of the hands is slightly larger than the other. The sculptor did not expect the hands to look as such, but he does not find the detail unpleasant; thus, the detail is not a mistake.
It is not wrong to have expectations, but one must ensure that they are reasonably aligned with reality. The sculptor would be unreasonable to expect every detail to match his ideal. Furthermore, having lower expectations leads to less details being regarded as mistakes. (Also, life would quickly become dull if expectations were always met to the fullest.)
Details could also be mistakingly labelled as mistakes. Is that curved nose truly unpleasant? Indeed, the matter is subjective. Consider a different perspective: that the curvature of the nose distinguishes the statue further. Seeing it this way could lessen the unpleasantness of the detail and perhaps even render it as pleasant.
Mistakes are inevitable, one way or another. Where it is impossible or unbearably arduous to undo them, one could accept that the universe will not always align with human ideals.