### Related Issue:
https://github.com/infiniflow/ragflow/issues/6653
### Environment:
Using nightly version [ece5903]
Elasticsearch database
Thanks for the review! My fault! I realize my initial testing wasn't
passed.
In graphrag/entity_resolution.py
`sub_connect_graph` is a set like` {'HELLO', 'Hi', 'How are you'}`,
Neither accessing `.nodes` nor `.nodes()` will work, **it still causes
`AttributeError: 'set' object has no attribute 'nodes'`**
In graphrag/general/extractor.py
The `list.extend() `method performs an in-place operation, directly
modifying the original list and returning ‘None’ rather than the
modified list.
Neither accessing
`sorted(set(node0_attrs[attr].extend(node1_attrs.get(attr, []))))` nor
`sorted(set(node0_attrs[attr].extend(node1_attrs[attr])))` will work,
**it still causes `TypeError: 'NoneType' object is not iterable`**
### Type of change
- [ ] Bug Fix AttributeError: graphrag/entity_resolution.py
- [ ] Bug Fix TypeError: graphrag/general/extractor.py
67330833af