Catch the correct type of translation error

So maybe the extra line for normal exceptions is more-or-less required?

```
use Scalar::Util qw(blessed);
...
eval { $translations = $self->provider->get_attribute('translations') };
if (my $error = Exception::Class->caught()) {
    die $error unless blessed $error;
    unless ($error->isa('NonexistentAttributeException')) {
        $error->rethrow();
    }
}
```