Registered methods errorHandling

Hi, in your documentation it says that error handling should work in the following way:

```
var req2=client.methods.jsonMethod(function(data,response){
    // parsed response body as js object
    console.log(data);
    // raw response
    console.log(response);
});

// handling specific req2 errors
req2.on('error',function(err){
    console.log('something went wrong on req2!!', err.request.options);
});
```

But in this case, ```req2``` is undefined. 

This was all caused by a missing return.