NPE crash on startup on Android N

[barbeau]

Summary:

When starting master branch or v2.1.4 on Android N device, it crashes with following stack trace:

 FATAL EXCEPTION: main
 Process: com.android.gpstest, PID: 26801
 java.lang.RuntimeException: Unable to resume activity {com.android.gpstest/com.android.gpstest.GpsTestActivity}: java.lang.NullPointerException
     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3400)
     at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:3440)
     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2713)
     at android.app.ActivityThread.-wrap12(ActivityThread.java)
     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
     at android.os.Handler.dispatchMessage(Handler.java:102)
     at android.os.Looper.loop(Looper.java:154)
     at android.app.ActivityThread.main(ActivityThread.java:6077)
     at java.lang.reflect.Method.invoke(Native Method)
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
  Caused by: java.lang.NullPointerException
     at com.android.internal.util.Preconditions.checkNotNull(Preconditions.java:94)
     at android.location.LocalListenerHelper.remove(LocalListenerHelper.java:76)
     at android.location.LocationManager.unregisterGnssNavigationMessageCallback(LocationManager.java:2171)
     at com.android.gpstest.GpsTestActivity.removeNavMessageListener(GpsTestActivity.java:503)
     at com.android.gpstest.GpsTestActivity.checkNavMessageOutput(GpsTestActivity.java:604)
     at com.android.gpstest.GpsTestActivity.onResume(GpsTestActivity.java:295)
     at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1269)
     at android.app.Activity.performResume(Activity.java:6768)
     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3377)
     at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:3440) 
     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2713) 
     at android.app.ActivityThread.-wrap12(ActivityThread.java) 
     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460) 
     at android.os.Handler.dispatchMessage(Handler.java:102) 
     at android.os.Looper.loop(Looper.java:154) 
     at android.app.ActivityThread.main(ActivityThread.java:6077) 
     at java.lang.reflect.Method.invoke(Native Method) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 

Steps to reproduce:

Start app on Android N device

Expected behavior:

Start up as normal

Observed behavior:

App crashes

Device and Android version:

Nexus 5X with Android N