Passport callback not being called

While trying to implement the passport-same authentication methods I have hit a roadblock. The callback function passed to the passport.authenticated function does not get called.

router.post("/saml/callback",
    function (req, res, next) {
        req.body.SAMLResponse = req.body.SAMLResponse.replace(/[\n\r]/g, "");
        next();
    },
    function (req, res, next) {
        console.log("Calling passport handler");
        console.log(req.body);
        try {
            const response = passport.authenticate("saml",
                {
                    failureRedirect: "/saml/error",
                    failureFlash: true
                }, (error, user, info) => {
                    console.log(error, user, info);
                    next();
                })(req, res, next);
            console.log(response);
        } catch(e) {
            console.log(e);
        }
        console.log("Line after passport handler");
    },
    function (req, res) {
        res.redirect("/saml/success");
    }
);

My express app hangs when entering this method but only with 1 specific saml provider (using https://samltest.id as test provider DOES work with the exact same code). It seems that an error occurs in this authenticate method but I cannot for the live of me find this error.

How do I get the error in this callback.

Log output:

Calling passport handler
{SAMLResponse: 'base64encoded saml response'}
undefined
Line after passport handler
Error: connect ETIMEDOUT ip:443

The problem turned out to not at all be in this piece of code but instead in the initiation of the saml provider.

I have a callback function in Strategy({cert: function(callback)....}); which tries to fetch the signing certificates for the saml response. The IDP was however not accessible from my SP due to it being a test server, therefor the callback never got called.

TL;DR; If you are using the cert key in your Strategy definition; and said key utilises a callback, check if that callback gets called!