If you get rejected for a code sample don't take it too hard. You're probably being graded by an engineer who views this part of their job as a distraction and tries to get it done as fast as possible. Sometimes code will fail to run due to some issue on their machine vs yours. Sometimes you'll hit their hobby-horse issue and be rejected for trivial reasons... Not that any of this is malicious. Grading the code sample is a one-way code review for a piece of code put together on the spur of the moment, with a tight deadline and no prior context. How many times have you received feedback on a PR that you've disagreed with? That disagreement gets resolved (or not) via discussion. But for a code sample there's no discussion, and everyone is trying to set the bar high, so one "slip up" is sufficient to reject the candidate.
Sometimes I read rejection comments and realize I would never pass the interview process at my own company, at least with certain individuals. It's depressing but that's just the way things are.