Fix crash when webserver is disabled

Author: mbm-OR

Source/RunActivity/Viewer3D/Cameras.cs

@@ -1080,7 +1080,7 @@ protected override void OnActivate(bool sameCamera)
             }
             else
             {
-                isVisibleTrainCarViewerOrWebpage = (Viewer.TrainCarOperationsWindow.Visible && !Viewer.TrainCarOperationsViewerWindow.Visible) || Viewer.TrainCarOperationsViewerWindow.Visible || (Viewer.TrainCarOperationsWebpage.Connections > 0 && Viewer.TrainCarOperationsWebpage.TrainCarSelected);
+                isVisibleTrainCarViewerOrWebpage = (Viewer.TrainCarOperationsWindow.Visible && !Viewer.TrainCarOperationsViewerWindow.Visible) || Viewer.TrainCarOperationsViewerWindow.Visible || (Viewer.TrainCarOperationsWebpage?.Connections > 0 && Viewer.TrainCarOperationsWebpage.TrainCarSelected);
             }
 
             if (attachedCar == null || attachedCar.Train != Viewer.SelectedTrain || carPosition != oldCarPosition)

Source/RunActivity/Viewer3D/Viewer.cs

@@ -789,7 +789,7 @@ public void Update(RenderFrame frame, float elapsedRealTime)
             // We need to do it also here, because passing from manual to auto a ReverseFormation may be needed
             if (Camera is TrackingCamera && Camera.AttachedCar != null && Camera.AttachedCar.Train != null && Camera.AttachedCar.Train.FormationReversed)
             {
-                IsFormationReversed = TrainCarOperationsWindow.Visible || TrainCarOperationsWebpage.Connections > 0;
+                IsFormationReversed = TrainCarOperationsWindow.Visible || TrainCarOperationsWebpage?.Connections > 0;
                 Camera.AttachedCar.Train.FormationReversed = false;
                 (Camera as TrackingCamera).SwapCameras();
             }
@@ -845,7 +845,7 @@ public void Update(RenderFrame frame, float elapsedRealTime)
             // Check if you need to swap camera
             if (Camera is TrackingCamera && Camera.AttachedCar != null && Camera.AttachedCar.Train != null && Camera.AttachedCar.Train.FormationReversed)
             {
-                IsFormationReversed = TrainCarOperationsWindow.Visible || TrainCarOperationsWebpage.Connections > 0;
+                IsFormationReversed = TrainCarOperationsWindow.Visible || TrainCarOperationsWebpage?.Connections > 0;
                 Camera.AttachedCar.Train.FormationReversed = false;
                 (Camera as TrackingCamera).SwapCameras();
             }