Why does the Imgur api occasionally give null data for a certain gallery pages?

Question

Occasionally when I attempt to get data about a subreddit gallery, it will return an empty list. I would consider this normal behavior, except most of the time when I try to request a page that doesn't exist, it returns the first page. For example - if I tried to get page 1000 of the paradoxplaza subreddit, it would return the equivalent of page 0. However, on some subreddits, it instead returns an empty list.