bugfix try for error on google play reported

java.lang.NullPointerException
at com.dlka.psonememorymanager.FileBrowser.fill(FileBrowser.java:122)
at com.dlka.psonememorymanager.FileBrowser.browseTo(FileBrowser.java:82)
at
com.dlka.psonememorymanager.FileBrowser.onListItemClick(FileBrowser.java:218)
at
com.dlka.psonememorymanager.FileBrowser$1.onItemClick(FileBrowser.java:45)
at android.widget.AdapterView.performItemClick(AdapterView.java:282)
at android.widget.AbsListView.performItemClick(AbsListView.java:1037)
at android.widget.AbsListView$PerformClick.run(AbsListView.java:2449)
at android.widget.AbsListView$1.run(AbsListView.java:3073)
at android.os.Handler.handleCallback(Handler.java:587)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:132)
at android.app.ActivityThread.main(ActivityThread.java:4123)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:491)
at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
at dalvik.system.NativeStart.main(Native Method)