is it possible to catch the following: if I have some template

```
<div ng-controller="SomeController">
    {{notthere}}
</div>

```

and `notthere` is not defined in the controllers `$scope`, can I have a callback fired to handle this? Like:

```
$scope.$catch(function(name) {
    // name === 'notthere'
    return 'someval';
}

```

BR,
Daniel