I looked at Reddit recently for the first time in a long time and the whole thing is a train wreck of marketing decisions built on shoddy code. If you look up a user who doesn’t exist[1] their karma reads “undefined”. If you navigate to their comments or about page (an info page for reddit accounts... why?) the site routes you to those pages with the value “undefined” as the username. But there is an actual user who chose that name so now you’re looking at their account page.
1.https://www.reddit.com/user/unidan