HelloWorld crashes on sending metrics

Got the master branch of the HelloWorld, and did the following:

• Start app on device, keep it in foreground
• send push (works fine)
• go into background
• send push
• click on notification in status bar
• see app crashing, all the time

From 'adb logcat' I got https://gist.github.com/matzew/79676e284d21b7b8a762