fix: Add null check for CurrentScenario in MobileControlSystem

This change introduces a check for `_roomCombiner.CurrentScenario` being `null`. When it is `null`, a `MobileControlMessage` is created with the type `/system/roomKey`, `clientId`, and `roomKey`, which is then sent to the client. This improves the handling of scenarios without a current scenario by ensuring relevant room key information is communicated.

src/PepperDash.Essentials.MobileControl/MobileControlSystemController.cs

@@ -2233,8 +2233,21 @@ namespace PepperDash.Essentials
                 return;
             }
 
+            if (_roomCombiner.CurrentScenario == null)
+            {
+                var message = new MobileControlMessage
+                {
+                    Type = "/system/roomKey",
+                    ClientId = clientId,
+                    Content = roomKey
+                };
+                SendMessageObject(message);
+                return;
+            }
+
             if (!_roomCombiner.CurrentScenario.UiMap.ContainsKey(roomKey))
             {
+
                 this.LogWarning(
                     "Unable to find correct roomKey for {roomKey} in current scenario. Returning {roomKey} as roomKey", roomKey);