For those who are passionate about their work, some of them they put their person in their code. As someone else pointed out in a comment in this thread, it is about acceptance that none of us is perfect, we don't/can't write perfect code and that is totally ok as long as you did what you could (both in terms of the output and the effort to improve the quality of the output). Unfortunately this is largely conditioned by upbringing so easier said than done. But awareness of this itself can be a helping factor in coping with criticism.