== Stack trace
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.util.ArrayList.isEmpty()' on a null object reference
at org.wikipedia.page.JsonPageLoadStrategy.updateCurrentBackStackItem(JsonPageLoadStrategy.java:502)
at org.wikipedia.page.JsonPageLoadStrategy.onSaveInstanceState(JsonPageLoadStrategy.java:215)
at org.wikipedia.page.PageViewFragmentInternal.onSaveInstanceState(PageViewFragmentInternal.java:424)
at android.support.v4.app.Fragment.performSaveInstanceState(Fragment.java:1936)
at android.support.v4.app.FragmentManagerImpl.saveFragmentBasicState(FragmentManager.java:1654)
at android.support.v4.app.FragmentManagerImpl.saveAllState(FragmentManager.java:1722)
at android.support.v4.app.FragmentActivity.onSaveInstanceState(FragmentActivity.java:527)
at org.wikipedia.page.PageActivity.onSaveInstanceState(PageActivity.java:789)
at android.app.Activity.performSaveInstanceState(Activity.java:1298)
at android.app.Instrumentation.callActivityOnSaveInstanceState(Instrumentation.java:1288)
at android.app.ActivityThread.callCallActivityOnSaveInstanceState(ActivityThread.java:3958)
== OTRS
https://ticket.wikimedia.org/otrs/index.pl?Action=AgentTicketZoom&TicketID=8463232
https://ticket.wikimedia.org/otrs/index.pl?Action=AgentTicketZoom&TicketID=8464533
https://ticket.wikimedia.org/otrs/index.pl?Action=AgentTicketZoom&TicketID=8465172
== Environment observed
**App version: ** 2.0.104-beta-2015-06-25
**Android OS versions:** 5.1.1, 4.4.2