Would be a good idea to update the subreddits

A lot has changed since 3 years ago, and a lot of subreddits in the redsim are now closed (I'm not talking about the recent Reddit protest), so it would be nice to update the comments database maybe

Start by locating the comments database and the subreddit data used by redsim, then identify which entries refer to closed subreddits. Compare those entries with current subreddit availability and update the affected data; the work is done when the database no longer contains the outdated subreddit references.

Written by the indexing model from the issue text.