Date picker throws exception when the activity is destroyed

    java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.Integer.intValue()' on a null object reference
        at com.wdullaer.materialdatetimepicker.date.DatePickerDialog.onSaveInstanceState(DatePickerDialog.java:299)
        at androidx.fragment.app.Fragment.performSaveInstanceState(Fragment.java:3183)
        at androidx.fragment.app.FragmentStateManager.saveBasicState(FragmentStateManager.java:680)
        at androidx.fragment.app.FragmentStateManager.saveState(FragmentStateManager.java:646)
        at androidx.fragment.app.FragmentStore.saveActiveFragments(FragmentStore.java:214)
        at androidx.fragment.app.FragmentManager.saveAllStateInternal(FragmentManager.java:2318)
        at androidx.fragment.app.Fragment.performSaveInstanceState(Fragment.java:3185)
        at androidx.fragment.app.FragmentStateManager.saveBasicState(FragmentStateManager.java:680)
        at androidx.fragment.app.FragmentStateManager.saveState(FragmentStateManager.java:646)
        at androidx.fragment.app.FragmentStore.saveActiveFragments(FragmentStore.java:214)
        at androidx.fragment.app.FragmentManager.saveAllStateInternal(FragmentManager.java:2318)
        at androidx.fragment.app.FragmentManager.lambda$attachController$0$androidx-fragment-app-FragmentManager(FragmentManager.java:2572)
        at androidx.fragment.app.FragmentManager$$ExternalSyntheticLambda0.saveState(Unknown Source:2)
        at androidx.savedstate.SavedStateRegistry.performSave(SavedStateRegistry.java:227)
        at androidx.savedstate.SavedStateRegistryController.performSave(SavedStateRegistryController.java:74)
        at androidx.activity.ComponentActivity.onSaveInstanceState(ComponentActivity.java:329)
        at android.app.Activity.performSaveInstanceState(Activity.java:2233)
        at android.app.Instrumentation.callActivityOnSaveInstanceState(Instrumentation.java:1489)
        at android.app.ActivityThread.callActivityOnSaveInstanceState(ActivityThread.java:5574)
        at android.app.ActivityThread.callActivityOnStop(ActivityThread.java:4947)
        at android.app.ActivityThread.performStopActivityInner(ActivityThread.java:4912)
        at android.app.ActivityThread.handleStopActivity(ActivityThread.java:4986)
        at android.app.servertransaction.StopActivityItem.execute(StopActivityItem.java:40)
        at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:176)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:97)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2108)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:236)
        at android.app.ActivityThread.main(ActivityThread.java:7876)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:656)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:967)

    Steps to reproduce:
       Open date picker dialog.  
       Minimize app (don't keep activities should be enabled)

wdullaer / MaterialDateTimePicker

Date picker throws exception when the activity is destroyed #748