fix: correctly add nodes to chunks [COG-1370] (#568)

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## Description
- Fix expand_with_nodes_and_edges to correctly add nodes to chunks
## DCO Affirmation
I affirm that all code in every commit of this pull request conforms to
the terms of the Topoteretes Developer Certificate of Origin


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Refactor**
- Enhanced the internal processing for data associations to ensure more
reliable and consistent handling of connections.
- Streamlined the logic to better manage edge cases, improving overall
stability and error handling.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

cognee/modules/graph/utils/expand_with_nodes_and_edges.py

@@ -19,6 +19,7 @@ def expand_with_nodes_and_edges(
         existing_edges_map = {}
 
     added_nodes_map = {}
+
     relationships = []
 
     for index, data_chunk in enumerate(data_chunks):
@@ -53,12 +54,14 @@ def expand_with_nodes_and_edges(
                     description=node.description,
                 )
 
-                if data_chunk.contains is None:
-                    data_chunk.contains = []
+                added_nodes_map[f"{str(node_id)}_entity"] = entity_node
+            else:
+                entity_node = added_nodes_map[f"{str(node_id)}_entity"]
 
-                data_chunk.contains.append(entity_node)
+            if data_chunk.contains is None:
+                data_chunk.contains = []
 
-                added_nodes_map[f"{str(node_id)}_entity"] = entity_node
+            data_chunk.contains.append(entity_node)
 
         # Add relationship that came from graphs.
         for edge in graph.edges: