Route param error handle

```
var webapps = express.Router();
module.exports = webapps;

function handleError(err, req, res, next) {
//this function is not executed
res.send("hello");
next();
}

webapps.param("app", function(req, res, next, name) {
next("asfaf");
});

webapps.route("/:app")
.all(handleError);
```

I am expected handleError to be executed and send a response of "hello", but instead "asfaf" is being send with status 500.