Yes, many theses have mistakes. Some even have intentional errors. How a given work is judged depends on many factors, too numerous to list. If it was an honest answer then some rework will lead to a more valid result. If that valid result is essentially the same as what you wrote, it will almost certainly be dismissed as an oversight.
But you can't change the past. It is what it is. You could, perhaps, produce a publication based on your thesis work in which you cite the thesis and correct the error.
Ultimately a reader can accept your work as acceptable if not perfect or reject it. You have no control over that. Someone who tries to reproduce your results and comes up with very different results will probably write about it in their own publication. You should be the one to do this instead.