Авторизация по логину и по email

<!-- <div class="form-group fill-animate" data-sid="USER_LOGIN_POPUP">
   <label class="font_14" for="USER_LOGIN_POPUP<?=$rand?>">
            <span><?=GetMessage("AUTH_LOGIN")?> <span class="required-star">*</span></span>
        </label>
   <div class="input">
            <input type="text" name="USER_LOGIN" id="USER_LOGIN_POPUP<?=$rand?>" 
                   class="form-control required" maxlength="50" 
                   value="<?=$arResult["USER_LOGIN"]?>" 
                   autocomplete="on" tabindex="1"/>
   </div>
</div>  -->


<!-- New code for Authorization with login/email -->
<div class="form-group fill-animate" data-sid="USER_LOGIN_OR_EMAIL">
    <label class="font_14" for="USER_LOGIN_OR_EMAIL_POPUP<?=$rand?>">
       <span>Введите логин или email<span class="required-star">*</span></span>
    </label>
    <div class="input">
        <input type="text" name="USER_LOGIN_OR_EMAIL" 
               id="USER_LOGIN_OR_EMAIL_POPUP<?=$rand?>" 
               class="form-control required" maxlength="50" 
               value="" autocomplete="on" tabindex="1" placeholder='login или email'/>
    </div>
</div> 

if(
        CModule::IncludeModule("security")
        && Mfa\Otp::isOtpRequired()
        && $_REQUEST["login_form"] <> "yes"
    )
    {
        $arResult["FORM_TYPE"] = "otp";

        $arResult["REMEMBER_OTP"] = (COption::GetOptionString('security', 'otp_allow_remember') === 'Y');

        $arResult["CAPTCHA_CODE"] = false;
        if(Mfa\Otp::isCaptchaRequired())
        {
            $arResult["CAPTCHA_CODE"] = $APPLICATION->CaptchaGetCode();
        }
        if(Mfa\Otp::isOtpRequiredByMandatory())
        {
            $arResult['ERROR_MESSAGE'] = array("MESSAGE" => GetMessage("system_auth_form_otp_required"), "TYPE" => "ERROR");
        }
    }
    else
    {
        $arResult["FORM_TYPE"] = "login";

// КАСТОМИЗАЦИЯ --- ВСТАВЛЯЕМ ЛОГИКУ ПОДМЕНЫ ДАННЫХ ДЛЯ АВТОРИЗАЦИИ ПО EMAIL ИЛИ ЛОГИНУ ---
        
        if(
            $_SERVER["REQUEST_METHOD"] === "POST"
            && isset($_REQUEST["AUTH_FORM"]) && $_REQUEST["AUTH_FORM"] === "Y"
            && isset($_REQUEST["TYPE"]) && $_REQUEST["TYPE"] === "AUTH"
        )
        {
            if(!empty($_POST["USER_LOGIN_OR_EMAIL"]))
            {
                $loginOrEmail = trim($_POST["USER_LOGIN_OR_EMAIL"]);

                // Если строка формально похожа на email (проверка filter_var)
                if(filter_var($loginOrEmail, FILTER_VALIDATE_EMAIL))
                {
                    // Ищем пользователя по полю EMAIL
                    $rsUser = CUser::GetList(
                        ($by = 'ID'),
                        ($order = 'ASC'),
                        ["=EMAIL" => $loginOrEmail]
                    );
                    if($arUser = $rsUser->Fetch())
                    {
                        // Подменяем стандартное поле, с которым работает Bitrix
                        $_POST["USER_LOGIN"] = $arUser["LOGIN"];
                    }
                    else
                    {
                        // Если не нашли по email, всё равно подставим исходное (пусть будет ошибка "Неверный логин/пароль")
                        $_POST["USER_LOGIN"] = $loginOrEmail;
                    }
                }
                else
                {
                    // Иначе считаем, что это логин
                    $_POST["USER_LOGIN"] = $loginOrEmail;
                }
            }
        }

 // КОНЕЦ КАСТОМИЗАЦИИ

$arVarExcl = array("USER_LOGIN"=>1, "USER_PASSWORD"=>1, "backurl"=>1, "auth_service_id"=>1, "TYPE"=>1, "AUTH_FORM"=>1);
$arResult["GET"] = array();
$arResult["POST"] = array();
foreach($_POST as $vname=>$vvalue) {