fix: check for grant code in mobileadduiclient

If the grant code was not provided, the `mobileadduiclient` console
command would fail silently. The command now checks that the correct
number of arguments was provided and prints an error to the console of
one is missing

src/PepperDash.Essentials.MobileControl/WebSocketServer/MobileControlWebsocketServer.cs

@@ -679,6 +679,14 @@ namespace PepperDash.Essentials.WebSocketServer
             }
 
             var values = s.Split(' ');
+
+            if(values.Length < 2)
+            {
+                CrestronConsole.ConsoleCommandResponse("Invalid number of arguments.  Please provide a room key and a grant code");
+                return;
+            }
+
+
             var roomKey = values[0];
             var grantCode = values[1];