Poke around in your feeds table. I bet you'll find a post with an empty url or shortened url.
Get comfortable with the data underneath this app. It's a really a simple structure. When you see an error like this, that means there's some bad data being processed.
The good news is no matter what this will eventually clear, since it's only dealing with the 40 most recent posts.
And the Counts page was compeltely broken a week ago.
Dave