DeckPicker: onQueryTextChange - NullPointerException on filter

[david-allison]

https://ankidroid.org/acra/app/1/bug/253121/report/f6ecbbf9-859d-40bb-b281-acbd2572d01a

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Filter.filter(java.lang.CharSequence)' on a null object reference
	at com.ichi2.anki.DeckPicker$setupSearchIcon$2$1.onQueryTextChange(DeckPicker.java:932)
	at androidx.appcompat.widget.SearchView.onTextChanged(SearchView.java:1198)
	at androidx.appcompat.widget.SearchView$10.onTextChanged(SearchView.java:1736)
	at android.widget.TextView.sendOnTextChanged(TextView.java:13051)
	at android.widget.TextView.setText(TextView.java:7784)
	at android.widget.TextView.setText(TextView.java:7596)
	at android.widget.EditText.setText(EditText.java:233)
	at android.widget.TextView.setText(TextView.java:7533)
	at androidx.appcompat.widget.SearchView.onActionViewExpanded(SearchView.java:1312)
	at androidx.appcompat.widget.Toolbar$ExpandedActionViewMenuPresenter.expandItemActionView(Toolbar.java:2748)
	at androidx.appcompat.view.menu.MenuBuilder.expandItemActionView(MenuBuilder.java:1363)
	at androidx.appcompat.view.menu.MenuItemImpl.expandActionView(MenuItemImpl.java:828)
	at androidx.appcompat.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:989)
	at androidx.appcompat.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:974)
	at androidx.appcompat.widget.ActionMenuView.invokeItem(ActionMenuView.java:620)
	at androidx.appcompat.view.menu.ActionMenuItemView.onClick(ActionMenuItemView.java:155)
	at android.view.View.performClick(View.java:8037)
	at android.view.View.performClickInternal(View.java:8006)
	at android.view.View.-$$Nest$mperformClickInternal(Unknown Source)
	at android.view.View$PerformClick.run(View.java:32003)
	at android.os.Handler.handleCallback(Handler.java:996)
	at android.os.Handler.dispatchMessage(Handler.java:110)
	at android.os.Looper.loopOnce(Looper.java:210)
	at android.os.Looper.loop(Looper.java:302)
	at android.app.ActivityThread.main(ActivityThread.java:9652)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:601)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1062)

[Giyutomioka-SS]

looking into this!

[david-allison]

To follow on from the PR:

This crash report didn't have a stack trace. Finding a matching one which does would be a great first step

From then it should be easier to understand or reproduce

[mikehardy]

Reproduction of the logic:

• you need a large device to switch in to our fragmented layout on DeckPicker
• you need enough decks in your deck list that the search icon shows up
• you click search and start typing: that is the thing that triggers onQueryTextChange

However, the only time I could see the adapter being null is if DeckPicker::onCreate wasn't called, because if it is called and did not throw an exception or other catastrophic error it will set the recyclerView.adapter to our DeckAdapter in onCreate

And I don't see where else that could be set to null, such that the adapter wouldn't be there when we asked it to filter

All I can think to do here is to guard against null (WHY ARE WE USING !! THERE !?) and sendExceptionReport for triage