Crash when viewing a cached item whose feed has been deleted

I had a feed and its items were cached in the app. I removed the feed from the server but didn't clear the cache. I updated the app to fetch the new feeds (which also removed the feed that was deleted in the server). Now whenever I view one of the cached items whose feed was deleted I get a message that the app crashed. It would be nice to remove cached items when a feed is removed as well.