I have a question about Naver map.

private final NMapLocationManager.OnLocationChangeListener onMyLocationChangeListener = new NMapLocationManager.OnLocationChangeListener() {

        @Override
        public boolean onLocationChanged(NMapLocationManager locationManager, NGeoPoint myLocation) {

            if (mMapController != null) {
                mMapController.animateTo(myLocation);
            }
            Log.d("myLog", "myLocation  lat " + myLocation.getLatitude());
            Log.d("myLog", "myLocation  lng " + myLocation.getLongitude());


            findPlacemarkAtLocation(myLocation.getLongitude(), myLocation.getLatitude());
            //Translate latitudes to addresses
            return true;
        }

Currently, Naver map is implemented to search the current location through markers through API. However, if you press the Back button on the map screen, the application stops immediately.

Below is the error screen.

FATAL EXCEPTION: main Process: com.kim.bisos, PID: 19493 java.lang.IllegalStateException: findPlacemarkAtLocation() could not be invoked prior to setMapDataProviderListener(). at com.nhn.android.maps.NMapContext.findPlacemarkAtLocation(NMapContext.java) at com.nhn.android.maps.NMapActivity.findPlacemarkAtLocation(NMapActivity.java) at `

`com.kim.bisos.NaverMyLocation$2.onLocationChanged(NaverMyLocation.java:180)

com.nhn.android.maps.NMapLocationManager.onLocationChanged(NMapLocationManager.java) at android.location.LocationManager$ListenerTransport._handleMessage(LocationManager.java:281) at android.location.LocationManager$ListenerTransport.access$000(LocationManager.java:210) at android.location.LocationManager$ListenerTransport$1.handleMessage(LocationManager.java:226) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:145) at android.app.ActivityThread.main(ActivityThread.java:5951) at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)

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I think the part marked in dark color means an error. I'd really appreciate your help.