private void login()
        {
            if (!DBController.TryGetCustomerByEmail(txtEmail.Text, out Customer c))
            {
                Feedback.ErrorDatabaseConnection();
                return;
            }

            if (c != null)
            {
                if (SecurePasswordHasher.Verify(txtPassword.Text, c.PasswordHash))
                {
                    FormController.CurrentCustomer = c;
                    c = null;
                    FormController.StartView.Close();
                    return;
                }
            }
            Feedback.ErrorInvalidLogin();
        }