java.lang.Error: FATAL EXCEPTION [main]

[tahir90]

On sign in it crashes and when i reopen the app it was already signed in then i click on leaderboardsUI or AchievementsUi it opens the UI fine but again on pressing back button it crashes with the same error which is as follows:

02-07 10:22:47.660: E/AndroidRuntime(31986): FATAL EXCEPTION: main
02-07 10:22:47.660: E/AndroidRuntime(31986): java.lang.Error: FATAL EXCEPTION [main]
02-07 10:22:47.660: E/AndroidRuntime(31986): Unity version : 4.2.1f4
02-07 10:22:47.660: E/AndroidRuntime(31986): Device model : samsung GT-I9300
02-07 10:22:47.660: E/AndroidRuntime(31986): Device fingerprint: samsung/m0xx/m0:4.1.2/JZO54K/I9300XXELLB:user/release-keys
02-07 10:22:47.660: E/AndroidRuntime(31986): Caused by: java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=9002, result=0, data=null} to activity {com.pepperpk.skitrix/com.nerdiacs.nerdgpgplugin.NerdUnityPlayerActivity}: java.lang.NullPointerException
02-07 10:22:47.660: E/AndroidRuntime(31986): at android.app.ActivityThread.deliverResults(ActivityThread.java:3182)
02-07 10:22:47.660: E/AndroidRuntime(31986): at android.app.ActivityThread.handleSendResult(ActivityThread.java:3225)
02-07 10:22:47.660: E/AndroidRuntime(31986): at android.app.ActivityThread.access$1100(ActivityThread.java:140)
02-07 10:22:47.660: E/AndroidRuntime(31986): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1275)
02-07 10:22:47.660: E/AndroidRuntime(31986): at android.os.Handler.dispatchMessage(Handler.java:99)
02-07 10:22:47.660: E/AndroidRuntime(31986): at android.os.Looper.loop(Looper.java:137)
02-07 10:22:47.660: E/AndroidRuntime(31986): at android.app.ActivityThread.main(ActivityThread.java:4898)
02-07 10:22:47.660: E/AndroidRuntime(31986): at java.lang.reflect.Method.invokeNative(Native Method)
02-07 10:22:47.660: E/AndroidRuntime(31986): at java.lang.reflect.Method.invoke(Method.java:511)
02-07 10:22:47.660: E/AndroidRuntime(31986): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
02-07 10:22:47.660: E/AndroidRuntime(31986): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
02-07 10:22:47.660: E/AndroidRuntime(31986): at dalvik.system.NativeStart.main(Native Method)
02-07 10:22:47.660: E/AndroidRuntime(31986): Caused by: java.lang.NullPointerException
02-07 10:22:47.660: E/AndroidRuntime(31986): at com.nerdiacs.nerdgpgplugin.NerdUnityPlayerActivity.onActivityResult(NerdUnityPlayerActivity.java:30)
02-07 10:22:47.660: E/AndroidRuntime(31986): at android.app.Activity.dispatchActivityResult(Activity.java:5390)
02-07 10:22:47.660: E/AndroidRuntime(31986): at android.app.ActivityThread.deliverResults(ActivityThread.java:3178)
02-07 10:22:47.660: E/AndroidRuntime(31986): ... 11 more

please have a look and provide a solution for this issue.thanks!

Regards,
Muhammad Tahir Ashraf