Android 5.1 crashes when notification arrives

I’m testing an Ionic V3 app on Samsung Galaxy S4 (running Android 5.1), and it works fine, except that every time it receives a notification, the whole phone crashes with the error “Unfortunately, System UI has stopped”. After closing the error, it pops up again and again in an endless cycle, rendering the phone useless until I restart it.

Any ideas why, or how I can resolve it? The app uses phonegap-plugin-push to handle notifications.