Looks like you have an empty session list. Have you ever used Safari? Quick workaround might be to pop open Safari once (and browse a little) and then try again.
Why on earth would anyone downvote this comment? The lack of a Safari user profile is the most obvious potential issue here, based on the backtrace.
That's the precise problem I had. Opening Safari got me one step closer and then another failure. I wanted to run all options but got tired of all these errors so I commented out ParseSafari, ParseFirefox, and ParseChrome calls inside the ParseBrowsers function. I could've left Firefox or Chrome but not wanting to shut Chrome down or not using Firefox much, I didn't want to go through this again for each browser.