clientrpc function gives null reference after client disconnects from host

Hi,

I having some trouble with my host and the client. After the client disconnects from the host I got a null reference at the call of the RpcUpdateMapProperties in the MapManager. I think it comes the function will be continuously called. But I am not sure.

 public class MapManager : NetworkBehaviour {
 
     private Camera mainCameraToUse;
     private MapboxQuadTreeBasicMap basicMap;
     private MapboxQuadTreeCameraMovement cameraMovement;
     private QuadTreeTileProvider quadTreeTileProvider;
 
     private UiController uiController;
 
     public override void OnStartClient()
     {
         if (isServer)
             return;
 
         InitializeClientCamera();
 
         basicMap = FindObjectOfType<MapboxQuadTreeBasicMap>();
         cameraMovement = FindObjectOfType<MapboxQuadTreeCameraMovement>();
         quadTreeTileProvider = FindObjectOfType<QuadTreeTileProvider>();
 
         base.OnStartClient();
     }
 
     public override void OnStartServer()
     {
         InitializeHostCamera();
 
         basicMap = FindObjectOfType<MapboxQuadTreeBasicMap>();
 
         cameraMovement = FindObjectOfType<MapboxQuadTreeCameraMovement>();
         cameraMovement.OnUpdateMapReceived += OnReceivedUpdatedMapProperties;
 
         uiController = FindObjectOfType<UiController>();
         uiController.OnReceivedCenterLocation += OnReceivedLocationChanged;
 
 
         quadTreeTileProvider = FindObjectOfType<QuadTreeTileProvider>();
         
         base.OnStartServer();
     }
 
     [Server]
     private void InitializeHostCamera()
     {
         mainCameraToUse = GameObject.Find("MapCamera").GetComponent<Camera>();
         mainCameraToUse.tag = "MainCamera";
         mainCameraToUse.depth = -1;
     }
 
     [Client]
     private void InitializeClientCamera()
     {
         mainCameraToUse = GameObject.Find("ARCamera").GetComponent<Camera>();
         mainCameraToUse.tag = "MainCamera";
         mainCameraToUse.depth = -1;
     }
 
     [Server]
     public void OnReceivedUpdatedMapProperties(Vector2d latlong, float zoom)
     {
         RpcUpdateMapProperties(latlong.x, latlong.y, zoom);
     }
 
     [Server]
     public void OnReceivedLocationChanged(Vector2d newCenterPoint)
     {
         cameraMovement.SetMapToLocation(newCenterPoint);
 
         RpcUpdateLocationChanged(newCenterPoint.x, newCenterPoint.y);
     }
 
     [ClientRpc]
     private void RpcUpdateLocationChanged(double latitude, double longitude)
     {
         Vector2d centerLatitudeLongitude = new Vector2d(latitude, longitude);
 
         cameraMovement.SetMapToLocation(centerLatitudeLongitude);
     }
 
     [ClientRpc]
     private void RpcUpdateMapProperties(double latitude, double longitude, float zoom)
     {
         Vector2d latlong = new Vector2d(latitude, longitude);
         quadTreeTileProvider.UpdateMapProperties(latlong, zoom);
     }
 
   
     private void OnDestroy()
     {
         if (isClient)
             return;
 
         cameraMovement.OnUpdateMapReceived -= OnReceivedUpdatedMapProperties;
         uiController.OnReceivedCenterLocation -= OnReceivedLocationChanged;
     }

Any help will be appreciated.