node-mysql error handling

router.post('/notes2', function(req, res) {

    var note_post = {
        title: req.body.title,
        body: req.body.body,
        author_id: req.body.author_id
    };

    // get a connection from the pool
    createConnection(function(err, connection) {
        if (err) {
            console.log(err);
            res.send({ success: false, message: 'database error', error: err });
            return;
        }

        // set up error listener for the connection
        connection.on('error', function(err) {
            console.log(err);
            res.send({ success: false, message: 'database error', error: err });
            return;
        });

        // create a common rollback function
        var rollback = function(err, message) {
            console.log(err);
            connection.rollback(function() {
                connection.release();
            });
            res.send({ success: false, message: message, error: err });
        }

        // start a transaction
        connection.beginTransaction(function(err) {
            if (err) {
                return rollback(err, 'start transaction error');
            }

            // execute a query
            connection.query("INSERT INTO notes SET ?", note_post, function(err, result) {
                if (err) {
                    return rollback(err, 'query error');
                }

                var insertId = result.insertId;

                // execute another query
                connection.query("UPDATE authors SET num_notes = num_notes + 1 WHERE id = ?", req.body.author_id, function(err, result) {
                    if (err) {
                        return rollback(err, 'query error');
                    }

                    // commit the transaction
                    connection.commit(function(err) {
                        if (err) {
                            return rollback(err, 'commit error');
                        }

                        connection.release();

                        res.setHeader('Location', '/test/notes/' + insertId);
                        res.status(201).send({ success: true });
                    });
                });
            });
        });
    });
});