anchor.diff:      if (link.leader == null) {
         return showWhenUnlinked ? super.findAll<S>(regionOffset - unlinkedOffset) : <S>[];
       }
  -    return super.findAll<S>(_transformOffset<S>(regionOffset));
  +    final Offset transformedOffset = _transformOffset<S>(regionOffset);
  +    if (transformedOffset == null) {
  +      return <S>[];
  +    }
  +    return super.findAll<S>(transformedOffset);
     }
   
     /// The transform that was used during the last composition phase.
  
positive.code: 
    @override
    S find<S>(Offset regionOffset) {
      final Iterable<S> all = findAll<S>(regionOffset);
      if (all.isEmpty) {
        return null;
      }
      return all.first;
    }
  
    @override
  
negative.code: 
    @override
    S find<S>(Offset regionOffset) {
      if (!clipPath.contains(regionOffset))
        return null;
      return super.find<S>(regionOffset);
    }
  
    @override
  