I think it makes sense to call `next(err)` here because if we did want to do some special error rendering, it seems like it's possible to add additional middleware like
```javascript
app.get('/badges/', [api('getBadges'), specialErrorHandler], function(req, res, next){ ... });
```
where `specialErrorHandler` has a `function(err, req, res, next){}` signature. So then we can start by letting errors drop through to a default error handler, and customize with special error displays per route later if that's useful.