public async Task <Tuple <bool, ErrorMessage> > UpdateUsername(int accountId, string newUsername)
{
if (!await _validationService.UserExists(accountId))
{
return(new Tuple <bool, ErrorMessage>(false, ErrorMessage.UserDoesNotExist));
}
await _userAccountService.ChangeUsername(accountId, newUsername);
return(new Tuple <bool, ErrorMessage>(true, ErrorMessage.None));
}