Heartbeat crashes if OSX user picture not set
I had the same problem as @christian in this thread.
Because I was running Heartbeat from XCode I could see it crashed because it couldn't find my OSX user account picture. I checked and found out I didn't have one set. After I set a user account picture I tried again and it worked perfectly.
Maybe some kind of fallback image needs to be provided to get users without a set OSX picture past this step.