Correct way to "do nothing"

Hello, and first of all thanks for the very nice library :).

I have a simple use case, I want to authenticate using passport and if the user is authenticated, the function should do nothing. It will run as lambda@edge at `ViewerRequest` for cloudfront.

What is the correct way to do nothing, return or call one of the response methods (to set `200`, something like that)?

```javascript
// ... (passport / express setup)

app.get('*', (req, res) => {
if (req.isAuthenticated()) {
return; // What should come here?
} else {
res.redirect('/login');
}
})
```

Start at the app.get('*') callback and review the repository's Express and Lambda@Edge integration guidance. Determine how an authenticated ViewerRequest should continue without a redirect, then document the supported behavior and a clear completion example.

Scritto dal modello di indicizzazione a partire dal testo della issue.