NullPointerException when Activity was killed in background and try to reopen it

[WebShaper]

I get a Nullpointer Exception when:

1. Enabling the Settings > System > Developer options > Don’t keep activities option. The activity gets killed when leaving it.
2. Open the app and open the Popup with all the SuperNova emoji Icons.
3. Press Home button to leave the app.
4. Reopen the App.

It only happens when to Popup is open.

Fatal Exception: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object java.util.ArrayList.get(int)' on a null object reference
at android.support.v4.view.ViewPager.getChildDrawingOrder(ViewPager.java:798)
at android.view.ViewGroup.getAndVerifyPreorderedIndex(ViewGroup.java:1986)
at android.view.ViewGroup.populateChildrenForAutofill(ViewGroup.java:3712)
at android.view.ViewGroup.getChildrenForAutofill(ViewGroup.java:3698)
at android.view.ViewGroup.dispatchProvideAutofillStructure(ViewGroup.java:3680)
at android.view.ViewGroup.dispatchProvideAutofillStructure(ViewGroup.java:3686)
at android.view.ViewGroup.dispatchProvideAutofillStructure(ViewGroup.java:3686)
at android.view.ViewGroup.dispatchProvideAutofillStructure(ViewGroup.java:3686)
at android.view.ViewGroup.dispatchProvideAutofillStructure(ViewGroup.java:3686)
at android.app.assist.AssistStructure$WindowNode.(AssistStructure.java:510)
at android.app.assist.AssistStructure.(AssistStructure.java:1912)
at android.app.ActivityThread.handleRequestAssistContextExtras(ActivityThread.java:3175)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1913)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6944)
at java.lang.reflect.Method.invoke(Method.java)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:327)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1374)