Update middleware/api_client/src/middleware/api_client/api_client.py

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: Zalfsten

middleware/api_client/src/middleware/api_client/api_client.py

@@ -452,7 +452,10 @@ def _serialize_arc(cls, arc: "ARC | dict[str, Any] | str") -> dict[str, Any]:
             return arc
         if isinstance(arc, str):
             try:
-                return cast(dict[str, Any], json.loads(arc))
+                data = json.loads(arc)
+                if not isinstance(data, dict):
+                    raise ApiClientError(f"JSON string must represent a dictionary, got {type(data).__name__}")
+                return cast(dict[str, Any], data)
             except json.JSONDecodeError as e:
                 raise ApiClientError(f"Invalid JSON string provided for ARC: {e}") from e
         return cast(dict[str, Any], json.loads(arc.ToROCrateJsonString()))