private async void RegisterUser()
{
if (Password.Length < 4)
{
Error = "Password must be 4 characters or more. ";
}
else
{
User user = new User {
UserName = this.UserName, Password = this.Password
};
Error = await _serverUser.Register(user);
if (Error == string.Empty)
{
LoginSuccess(user);
}
}
}