public async Task StartApp()
        {
            if (!_accountManager.IsRegistered)
            {
                throw new InvalidOperationException();
            }


            var authResult = await Authorize();

            if (authResult.Result == AuthenticationResultType.NotRegistered)
            {
                _accountManager.Deregister();
                RegistrationRequested(this, EventArgs.Empty);
                return;
            }
        }