Android Question Crashlytics reports problem with Preference activity.

[tsteward]

Crashlytics gives the following error from users device.
Any idea what this is or where I begin to look. Obviously something to do with preference activity.
Seeing this on Galaxy S5 running Android 6.0.1 and Pixel XL running 8.1.0

Fatal Exception: java.lang.RuntimeException
Unable to start activity ComponentInfo{lishi.assistand.tony.stewardgmail.com/anywheresoftware.b4a.objects.preferenceactivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.util.Iterator java.util.ArrayList.iterator()' on a null object reference
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android.app.ActivityThread.performLaunchActivity (ActivityThread.java:3253)

android.app.ActivityThread.handleLaunchActivity (ActivityThread.java:3349)

android.app.ActivityThread.access$1100 (ActivityThread.java:221)

android.app.ActivityThread$H.handleMessage (ActivityThread.java:1794)

android.os.Handler.dispatchMessage (Handler.java:102)

android.os.Looper.loop (Looper.java:158)

android.app.ActivityThread.main (ActivityThread.java:7224)

java.lang.reflect.Method.invoke (Method.java)

com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run (ZygoteInit.java:1230)

com.android.internal.os.ZygoteInit.main (ZygoteInit.java:1120)

Caused by java.lang.NullPointerException
Attempt to invoke virtual method 'java.util.Iterator java.util.ArrayList.iterator()' on a null object reference
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anywheresoftware.b4a.objects.preferenceactivity$PreferenceScreenWrapper.createPreference (preferenceactivity.java:221)
(preferenceactivity.java:65)

android.app.Activity.performCreate (Activity.java:6876)

android.app.Instrumentation.callActivityOnCreate (Instrumentation.java:1135)

android.app.ActivityThread.performLaunchActivity (ActivityThread.java:3206)

android.app.ActivityThread.handleLaunchActivity (ActivityThread.java:3349)

android.app.ActivityThread.access$1100 (ActivityThread.java:221)

android.app.ActivityThread$H.handleMessage (ActivityThread.java:1794)

android.os.Handler.dispatchMessage (Handler.java:102)

android.os.Looper.loop (Looper.java:158)

android.app.ActivityThread.main (ActivityThread.java:7224)

java.lang.reflect.Method.invoke (Method.java)

com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run (ZygoteInit.java:1230)

com.android.internal.os.ZygoteInit.main (ZygoteInit.java:1120)

 

[Erel]

It can happen if you added an uninitialized category or screen.