Catch the correct type of translation error

Another option could be:

```perl
if (my $error = Exception::Class->caught()) {
    die $error unless UNIVERSAL::isa($error, 'NonexistentAttributeException');
}
```
That one avoids any issues if Exception::Class stomps on $@.

(If we want to possibly call rethrow(), we have to additionally check that the object is a type that can rethrow().)