500 Error: Cannot find module 'undefined'

Thanks for your example. It really helps.

There is an issue here. When I try to run option1, there is an error "500 Error: Cannot find module 'undefined'".

After I repalce the code in app.js

``` javascript
app.get('/todo', function(req, res){
res.render('todo', {title: "MongoDB Backed TODO App"});
});
```

with code like this

``` javascript
app.get('/todo', function(req, res){
res.sendfile(__dirname + '/public/static.html');
});
```

It works just fine. Why?
If it's an bug, would you fix it?