Default express api error handling middleware.

error-handling.js

/**
 * Handle application errors.
 *
 * NOTE: 500 status code is returned by default.
 *
 * To properly leverage this middleware, rather than return responses in your routes,
 * simply set a response status in the route and then pass the error object to `next`.
 * This middleware will catch that error and handle it in a consistent way across
 * the entire application. For example:
 *
 *     try {
 *       // look up something here
 *     } catch (err) {
 *       res.status(404);
 *       return next(err);
 *     }
 *
 * @see {@link https://expressjs.com/en/guide/error-handling.html}
 */
export function defaultErrorHandler(err, req, res, next) {
  if (res.headersSent) {
    return next(err);
  }

  console.error(err);
  return res.status((res.statusCode > 200 && res.statusCode) || 500).send({ message: err.message });
}

// use like so:
// The default error handler should come AFTER all routes to catch
// all application errors and handle them in a consistent manner.
app.use(defaultErrorHandler);