a pesudonym is somewhat unprofessional. I mean, certainly, if you are good enough, nobody cares, but for technical stuff? it's probably in your interest to publish cool stuff under your real name.

Now, at least for me, the times I embarrass myself I am talking about personal stuff or about politics. Using a pseudonym for that sort of thing is completely reasonable. I think "would I want this on my long-form resume?" is a good question to ask before posting something under your real name.

Generally, I think, technical mistakes are forgiven, especially if you admit or point out your mistake. There isn't much danger, I think, to coding using your real name.