fix: fields with null values serialized to empty dict (#636)

Author: dianagrecu-uipath

src/uipath_langchain/runtime/_serialize.py

@@ -14,9 +14,6 @@ def serialize_output(output: Any) -> Any:
     Returns:
         Dict[str, Any]: Serialized output as dictionary
     """
-    if output is None:
-        return {}
-
     # Handle LangGraph types
     if isinstance(output, Overwrite):
         return serialize_output(output.value)

src/uipath_langchain/runtime/runtime.py

@@ -456,14 +456,14 @@ def _create_breakpoint_result(
         return UiPathBreakpointResult(
             breakpoint_node=breakpoint_node,
             breakpoint_type=breakpoint_type,
-            current_state=serialize_output(graph_state.values),
+            current_state=serialize_output(graph_state.values) or {},
             next_nodes=next_nodes,
         )
 
     def _create_success_result(self, output: Any) -> UiPathRuntimeResult:
         """Create result for successful completion."""
         return UiPathRuntimeResult(
-            output=serialize_output(output),
+            output=serialize_output(output) or {},
             status=UiPathRuntimeStatus.SUCCESSFUL,
         )