The Camera should not throw NotConnected while connected

Instead when an image is not ready throw InvalidOperation

Author: DanielVanNoord

Camera.Simulator/Camera.cs

@@ -3245,7 +3245,7 @@ private void CheckReady(string identifier)
             if (!imageReady)
             {
                 Log.LogMessage(identifier, "image not ready");
-                throw new NotConnectedException("Can't read " + identifier + " when no image is ready");
+                throw new InvalidOperationException("Can't read " + identifier + " when no image is ready");
             }
         }