screen capture crash

08-08 17:31:13.172: D/AndroidRuntime(14390): Shutting down VM
08-08 17:31:13.172: E/AndroidRuntime(14390): FATAL EXCEPTION: main
08-08 17:31:13.172: E/AndroidRuntime(14390): Process: com.android.systemui, PID: 14390
08-08 17:31:13.172: E/AndroidRuntime(14390): java.lang.RuntimeException: Unable to destroy activity {com.android.systemui/com.android.systemui.media.MediaProjectionPermissionActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.AlertDialog.dismiss()' on a null object reference
08-08 17:31:13.172: E/AndroidRuntime(14390): 	at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:3975)
08-08 17:31:13.172: E/AndroidRuntime(14390): 	at android.app.ActivityThread.handleDestroyActivity(ActivityThread.java:3993)
08-08 17:31:13.172: E/AndroidRuntime(14390): 	at android.app.ActivityThread.access$1400(ActivityThread.java:178)
08-08 17:31:13.172: E/AndroidRuntime(14390): 	at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1524)
08-08 17:31:13.172: E/AndroidRuntime(14390): 	at android.os.Handler.dispatchMessage(Handler.java:111)
08-08 17:31:13.172: E/AndroidRuntime(14390): 	at android.os.Looper.loop(Looper.java:194)
08-08 17:31:13.172: E/AndroidRuntime(14390): 	at android.app.ActivityThread.main(ActivityThread.java:5637)
08-08 17:31:13.172: E/AndroidRuntime(14390): 	at java.lang.reflect.Method.invoke(Native Method)
08-08 17:31:13.172: E/AndroidRuntime(14390): 	at java.lang.reflect.Method.invoke(Method.java:372)
08-08 17:31:13.172: E/AndroidRuntime(14390): 	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:960)
08-08 17:31:13.172: E/AndroidRuntime(14390): 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
08-08 17:31:13.172: E/AndroidRuntime(14390): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.AlertDialog.dismiss()' on a null object reference
08-08 17:31:13.172: E/AndroidRuntime(14390): 	at com.android.systemui.media.MediaProjectionPermissionActivity.onDestroy(MediaProjectionPermissionActivity.java:169)
08-08 17:31:13.172: E/AndroidRuntime(14390): 	at android.app.Activity.performDestroy(Activity.java:6291)
08-08 17:31:13.172: E/AndroidRuntime(14390): 	at android.app.Instrumentation.callActivityOnDestroy(Instrumentation.java:1148)
08-08 17:31:13.172: E/AndroidRuntime(14390): 	at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:3962)
08-08 17:31:13.172: E/AndroidRuntime(14390): 	... 10 more