Can't set headers

I have some basic authentication in a route that when used is throwing a console error. The following is the error:

Error: Can't set headers after they are sent.
    at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:356:11)
    at ServerResponse.header

Here is the route where the error occurs. It only occurs when the "if" statement is true (the code within the if statement runs). When that doesn't run, I am not getting any error and the "home" view renders without error.

routes.get('/scan',  (req, res, next) => {
    const orderID = req.query.order;
    const token   = req.query.token;


    if( !hasAccess( token ) ) {
        res.status(401).send('Unauthorized');
    }

    res.render('home', {
                order
            });
}

via Jim M