gistfile1.txt

function dropUserCollection(callback) {
        console.log("dropUserCollection");
        user = reader_test_db.collection('user');
        if (undefined != user) {
            user.drop(function(err, reply) {
                console.log('user collection dropped');
                callback(0);
            });
        } else {
            callback(0);
        }
    },

Is the comma (,) on line 12 a typo?

Yes. It´s a typo.