BackgroundTask kills the app

[zoolle]

In Xcode logs I get the following error from time to time which shortly after end up with killing the app

[BackgroundTask] Background Task 208 ("Called by MapboxMobileEvents, from -[MMEUIApplicationWrapper beginBackgroundTaskWithExpirationHandler:]"), was created over 30 seconds ago. In applications running in the background, this creates a risk of termination. Remember to call UIApplication.endBackgroundTask(_:) for your task in a timely manner to avoid this.

Any idea what it should mean and how to prevent this from happening?