So, what to do if you were pretty stupid in one moment and accidentally typed a misspelled domain name during registration? Can I try to sell the domain, or it will be considered domain squatting?
I'd leave it. Since you as the owner of the idea misspelled it, visitors can repeat the mistake. Just point it to the right domain name.
Many will assume that you were not "stupid" at all, but rather were being coy and clever. In fact deliberate misspellings are trendy these days.
People misspell words when using Google and other search engines all of the time. That does not stop them from finding what they are looking for. So, you misspelt your domain name. Capitalize on it. If you misspelt it, there are probably hundreds of potential visitors that also misspelt it the same way. There are lots of stories of how an eBay seller misspelt something and lost hundreds, or even thousands, of dollars on the item because the buyers were limited to those buyers who misspelt the key word the same way.