明示承诺抛出错误

我正在使用带有去神化模块的Express。尝试异步呈现电子邮件模板时出错。

.then(function () {
     return denodeify(res.render)(path.resolve('verify-email'), {
         name: user.displayName,
         appName: config.app.title,
         mail: user.email,
         url: 'http://' + req.headers.host
     });
})
.then(function (emailHTML) {
     // code which is not executed
})
.catch(function (err) {
     // [TypeError: Cannot read property 'req' of undefined]
});

我试着在没有回调的情况下使用res.render，效果很好，但我需要在变量中输出电子邮件模板。我也不明白如何调试这部分代码。谢谢你的帮助！全代码

function sendVerificationEmail(user, req, res) {
    return denodeify(crypto.randomBytes)(20)
        .then(function (buffer) {
            user.verificationToken = buffer.toString('hex');
            return user.save();
        })
        .then(function () {
            user.password = undefined;
            user.salt = undefined;
            delete req.session.redirect_to;
            return denodeify(res.render)(path.resolve('modules/users/server/templates/verify-email'), {
                name: user.displayName,
                appName: config.app.title,
                mail: user.email,
                url: 'http://' + req.headers.host + '/api/auth/verify/' + user.verificationToken + "/" + user.email
            });
        })
        .then(function (emailHTML) {
            const mailOptions = {
                to: user.email,
                from: config.mailer.from,
                subject: 'Verify Email',
                html: emailHTML
            };
            return denodeify(smtpTransport.sendMail)(mailOptions);
        });
}
exports.updateAuthData = function (req, res, next) {
    const userId = req.session.userId;
    delete req.session.userId;
    if (!userId) {
        return res.status(401).send({
            message: 'No active session'
        });
    }
    let user;
    User.findById(userId)
        .then()
        .then((_user) => {
            user = _user;
            const fields = Object.keys(req.body);
            const neededFields = user.getMissingAuthFields();
            const missingFields = _.difference(fields, neededFields);
            if (missingFields.length !== 0) {
                throw new CustomError('Missing fields: ' + missingFields.join(', '))
            }
            for (let field of User.requiredAuthorizationFields) {
                if (!!user[field]) {
                    throw new CustomError('User already has ' + field);
                }
            }
            User.requiredAuthorizationFields.forEach((field) => user[field] = req.body[field]);
            return true;
        })
        .then(function () {
            return sendVerificationEmail(user, req, res);
        })
        .then(() => {
            res.send({
                message: 'An email has been sent to the provided email, please verify your account.'
            });
        })
        .catch(function (err) {
            res.status(400).send({
                message: 'Failure sending email'
            });
        })
};