Контроллер AngularJS вызывает контроллер MVC - это успешно, но выдает ошибку, которая содержит ноль

Question

У меня есть приложение AngularJS / MVC, которое вызывает метод контроллера MVC.Метод успешно отправляет электронное письмо, но переходит в функцию error, и переменная error имеет значение null.

Почему происходит сбой?Я пытался узнать больше об ошибке, используя другой вызов, но предупреждение не появляется при его использовании.Я думаю, потому что возвращаемое значение равно нулю и не может быть разрешено.

Вот метод контроллера AngularJS.

    $scope.BookMySeat = function (UserName, SeatNo) {
        if (UserName) {
             // The UserName is not empty. Check to see of it exists.
             dataService.ValidateUsername(UserName).success(function (output) {
                  if (output == -1)
                {
                    // The user name does NOT exist. Do the insert to the table.

                    $scope.onclick = !$scope.onclick;

                    console.log(UserName + SeatNo);

                    dataService.InsertSeat(UserName, slotNum, SeatNo).success(function (output) {
                        $scope.bookedSeatList = output;

                        var imageCollection = new Array(totalseat);
                        $scope.images = imageCollection;
                        $scope.imageUrlNotBooked = "../Images/RED.jpg";

                        $scope.bookcollscope = $scope.bookedSeatList;
                        console.log($scope.bookcollscope);
                        var imageCollection1 = new Array($scope.bookedSeatList);
                        $scope.images1 = imageCollection1;
                        $scope.imageUrlBooked = "../Images/GREEN.jpg";

                        // Alert.
                        alert("Seat number " + SeatNo + " has been booked for : " + UserName);

                        //----------------------------------------------------------------------------------------------------------
                        // Send an email using a MVC controller method.
                        // - Using $http to call to a MVC controller method.
                        //----------------------------------------------------------------------------------------------------------

                        var encodedQueryString = encodeURIComponent('emailAddress') + '=' + encodeURIComponent('dc4444@hotmail.com') + '&' + encodeURIComponent('type') + '=' + encodeURIComponent('I') + '&' + encodeURIComponent('seatNbr') + '=' + encodeURIComponent(SeatNo) + '&' + encodeURIComponent('slotNbr') + '=' + encodeURIComponent(0);
 
                        $http.get("/Home/SendAlertEmail?" + encodedQueryString).success(function (data) {
                            // Alert.
                            alert("An insert email was sent.");
                        }).error(function (error) {
                            // Error alert.
                            alert("Something went wrong with the insert - SendEmail. " + error);
                            console.log(error);
                        });

                        //$http.get("/Home/SendAlertEmail?" + encodedQueryString).success(function (data) {
                        //    // Alert.
                        //    alert("An insert email was sent.");
                        //}).error(function (xhr) {
                        //    // Error alert.
                        //    alert("Something went wrong with the insert - SendEmail. Status: " + xhr.status + ". Response Text: " + xhr.responseText);
                        //    console.log(error);
                        //});
                    }).error(function (output) {
                        $scope.error = true;
                    });
                }
                else
                {
                    // The user name exists.
                     alert("That passenger name exists. Please enter a UNIQUE passenger name in order to book a seat.");
                }
                console.log(output);
            }).error(function (output) {
                $scope.error = true;
            });
        }
        else
        {
            alert("The passenger name is empty. Please enter a passenger name in order to book a seat.");
        } 
    }

Вот метод контроллера MVC.

       public void SendAlertEmail([FromUri] string emailAddress, [FromUri]string type, [FromUri]int seatNbr, [FromUri]int slotNbr)
    {
        string strHtmlMessageBody = "";

        NetworkCredential NetworkCred = new NetworkCredential();
        System.Net.Mail.SmtpClient smtp = new SmtpClient();

        try
        {
            MailMessage mm = new MailMessage();

            mm.From = new MailAddress("xxxxx@hotmail.com");
            mm.Subject = "From the BookSeat Portal. Passenger Seat Information.";

            if (type == "I")
            {
                strHtmlMessageBody = "<p>Your passenger seat: " + seatNbr + " has been created by the system.</p>";
            }
            else
            {
                strHtmlMessageBody = "<p>Your passenger seat number: " + seatNbr + ", slot number: " + slotNbr + " has been deleted by the system.</p>";
            }

            mm.Body = strHtmlMessageBody;
            mm.IsBodyHtml = true;
            mm.To.Add(new MailAddress(emailAddress));

            smtp.Host = "smtp.live.com";
            smtp.EnableSsl = true;
            smtp.UseDefaultCredentials = true;
            smtp.Port = 587;
            NetworkCred.UserName = "xxxxx@hotmail.com";
            NetworkCred.Password = "yyyyyyy";

            smtp.Credentials = NetworkCred;
            smtp.Send(mm);
        }
        catch (SmtpException smtpEx)
        {
            throw new Exception("SMTP exception: " + smtpEx);
        }
        catch (Exception ex)
        {
            throw new Exception("Sending email exception: " + ex);
        }
    }

Вот отправленное письмо.