Removed a reference cell by returning a return code on each matched p…

…attern's result expression.

Src/Qaiain.CommandLine/Program.fs

@@ -199,14 +199,13 @@ let main argv =
 
     let handle msg = Mail.handle getMessage deleteMessage send msg
 
-    let exitCode = ref 0
     match queue |> AzureQ.dequeue with
     | Some(msg) ->
         match msg.AsString |> handle with
-        | Success _ -> queue.DeleteMessage msg
+        | Success _ ->
+            queue.DeleteMessage msg
+            0
         | Failure f ->
             f |> toString |> Console.Error.WriteLine
-            exitCode := 13
-    | _ -> ()
-
-    !exitCode // return an integer exit code
+            13
+    | _ -> 0