Android Question What could be the cause of this error (AdUtil.isViewVisible)?

[asales]

Sometimes I get this error below in Firebase Crashlytics.

I always check if the adview is initialized, when I check if adview is visible (to avoid policy issue when I show a dialog with another adview).

This error happened in a Nexus 5X with Android 6.0.1.
I think this phone is used by Google in tests, because I just published the new version of the app and this the first phone (and only phone until now) that raises this error.

What could be happen?

Any help are welcome. Thanks.

Fatal Exception: java.lang.NullPointerException:
Attempt to invoke virtual method 'int android.view.View.getVisibility()' on a null object reference
       at com.google.android.gms.ads.internal.util.AdUtil.isViewVisible(AdUtil.java:1123)
       at com.google.android.gms.ads.internal.activeview.PositionWatcher.fireMeasurements(PositionWatcher.java:360)
       at com.google.android.gms.ads.internal.activeview.PositionWatcher.lambda$fireMeasurementsPost$0$com-google-android-gms-ads-internal-activeview-PositionWatcher(PositionWatcher.java:140)
       at com.google.android.gms.ads.internal.activeview.PositionWatcher$$ExternalSyntheticLambda0.run(D8$$SyntheticClass)
       at android.os.Handler.handleCallback(Handler.java:739)
       at android.os.Handler.dispatchMessage(Handler.java:95)
       at com.google.android.gms.libs.punchclock.threads.TracingHandler.dispatchMessageTraced(TracingHandler.java:223)
       at com.google.android.gms.ads.internal.util.AdMobHandler.dispatchMessageTraced(AdMobHandler.java:39)
       at com.google.android.gms.libs.punchclock.threads.TracingHandler.dispatchMessage(TracingHandler.java:183)
       at android.os.Looper.loop(Looper.java:148)
       at android.app.ActivityThread.main(ActivityThread.java:5421)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

 

[agraham]

That's a very odd stack trace. I can't see any B4A references in it at all. It almost seems like it is an internal Android problem but I can't be absolutely sure.