in play-v29/src/main/scala/com/gu/googleauth/actions.scala [144:151]
private def requireTwoFactorAuthFor(userIdentity: UserIdentity)(checker: TwoFactorAuthChecker)(
implicit ec: ExecutionContext
): EitherT[Future, Result, UserIdentity] = EitherT {
checker.check(userIdentity.email).map(userHas2FA => if (userHas2FA) Right(userIdentity) else {
logger.warn(s"failed-oauth-callback : user-does-not-have-2fa")
Left(redirectWithError(failureRedirectTarget, "You do not have 2FA enabled"))
})
}