Mosby 3.1.0 NPEs in Activity#onDestroy()

After upgrading app to Mosby 3.1.0 crash analytics have started displaying crashes like:

java.lang.RuntimeException: Unable to destroy activity {p/p.a}: java.lang.NullPointerException: Attempt to invoke interface method 'void com.hannesdorfmann.mosby3.mvp.MvpPresenter.detachView()' on a null object reference
	at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:4299)
	at android.app.ActivityThread.handleDestroyActivity(ActivityThread.java:4317)
	at android.app.ActivityThread.-wrap6(ActivityThread.java)
	at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1569)
	at android.os.Handler.dispatchMessage(Handler.java:102)
	at android.os.Looper.loop(Looper.java:241)
	at android.app.ActivityThread.main(ActivityThread.java:6274)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'void com.hannesdorfmann.mosby3.mvp.MvpPresenter.detachView()' on a null object reference
	at com.hannesdorfmann.mosby3.mvp.delegate.ViewGroupMvpDelegateImpl.detachPresenterIfNotDoneYet(ViewGroupMvpDelegateImpl.java:301)
	at com.hannesdorfmann.mosby3.mvp.delegate.ViewGroupMvpDelegateImpl.onActivityDestroyed(ViewGroupMvpDelegateImpl.java:255)
	at android.app.Application.dispatchActivityDestroyed(Application.java:253)
	at android.app.Activity.onDestroy(Activity.java:1851)
	at android.support.v4.app.FragmentActivity.onDestroy(FragmentActivity.java:358)
	at android.support.v7.app.AppCompatActivity.onDestroy(AppCompatActivity.java:209)
	at p.a.onDestroy(a.java:)
	at android.app.Activity.performDestroy(Activity.java:6922)
	at android.app.Instrumentation.callActivityOnDestroy(Instrumentation.java:1154)
	at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:4286)
	... 9 more

Do not have the specific repro steps available yet, but reading the source in ViewGroupMvpDelegateImpl:

  private void destroyPresenterIfnotDoneYet() {
    if (!presenterDestroeyed) {
      P presenter = delegateCallback.getPresenter();
      presenter.destroy();

To me this looks like the code is assuming too much about the fragment/activity lifecycle - the fragment lifecycle has not reached MvpFragment#onCreate() where the presenter is created but the the activity gets destroyed for some other reason, and presenterDestroeyed defaults to false.

For what it’s worth, there’s also a typo in presenterDestroeyed.

[sockeqwe]

Working on it, along migrating to android x

[vladimirfx]

I don’t know actually. Stacktrace do not include either:

Caused by java.lang.NullPointerExceptionAttempt to invoke interface method 'void com.hannesdorfmann.mosby3.mvp.MvpPresenter.detachView()' on a null object reference Raw Text
--
  | com.hannesdorfmann.mosby3.ViewGroupMviDelegateImpl.detachPresenterIfNotDoneYet (ViewGroupMviDelegateImpl.java:275)
  | com.hannesdorfmann.mosby3.ViewGroupMviDelegateImpl.onActivityDestroyed (ViewGroupMviDelegateImpl.java:251)
  | android.app.Application.dispatchActivityDestroyed (Application.java:253)
  | android.app.Activity.onDestroy (Activity.java:1995)
  | android.support.v4.app.FragmentActivity.onDestroy (FragmentActivity.java:413)
  | android.support.v7.app.AppCompatActivity.onDestroy (AppCompatActivity.java:210)
  | android.app.Activity.performDestroy (Activity.java:7297)
  | android.app.Instrumentation.callActivityOnDestroy (Instrumentation.java:1250)
  | android.app.ActivityThread.performDestroyActivity (ActivityThread.java:4437)
  | android.app.ActivityThread.handleDestroyActivity (ActivityThread.java:4468)
  | android.app.ActivityThread.-wrap5 (Unknown Source)
  | android.app.ActivityThread$H.handleMessage (ActivityThread.java:1678)
  | android.os.Handler.dispatchMessage (Handler.java:106)
  | android.os.Looper.loop (Looper.java:171)
  | android.app.ActivityThread.main (ActivityThread.java:6651)
  | java.lang.reflect.Method.invoke (Method.java)
  | com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:547)
  | com.android.internal.os.ZygoteInit.main (ZygoteInit.java:824)