fix(redact_messages): guard against None output_items in Responses API redaction helpers

- Add early return guard for None or empty output_items in _redact_responses_api_output
- Add early return guard for None or empty output_items in _redact_responses_api_output_dict
- Add unit test verifying perform_redaction and helpers safely handle None output
- Fixes #43797

litellm/litellm_core_utils/redact_messages.py

@@ -219,6 +219,8 @@ def _redact_field_when_present(item: object, field: str) -> None:
 
 def _redact_responses_api_output(output_items):
     """Helper to redact ResponsesAPIResponse output items."""
+    if not output_items:
+        return
     for output_item in output_items:
         output_type = stream_item_field(output_item, "type")
         if getattr(output_item, "text", None) is not None:
@@ -295,7 +297,9 @@ def _redacted_responses_api_output_item(item: object, redacted_str: str) -> obje
     }
 
 
-def _redact_responses_api_output_dict(output_items: Sequence[object], redacted_str: str) -> Sequence[object]:
+def _redact_responses_api_output_dict(output_items: Sequence[object] | None, redacted_str: str) -> Sequence[object]:
+    if not output_items:
+        return []
     return [_redacted_responses_api_output_item(item, redacted_str) for item in output_items]
 
 

tests/unit/litellm_core_utils/test_redact_messages.py

@@ -899,6 +899,26 @@ class TestPerformRedaction:
         assert none_dict == {"type": "output_text", "text": None, "content": [{"text": None}]}
         assert real_dict == {"type": "output_text", "text": "real answer", "content": [{"text": "real part"}]}
 
+    def test_redact_responses_api_output_handles_none(self):
+        from litellm.litellm_core_utils.redact_messages import (
+            _redact_responses_api_output,
+            _redact_responses_api_output_dict,
+            _redact_streaming_response,
+        )
+
+        _redact_responses_api_output(None)
+        assert _redact_responses_api_output_dict(None, "redacted-by-litellm") == []
+
+        # Test dictionary output: None
+        result_dict = {"output": None}
+        redacted_dict = perform_redaction({}, result_dict)
+        assert redacted_dict["output"] is None
+
+        # Test object/streaming response output: None
+        streaming_obj = SimpleNamespace(output=None)
+        _redact_streaming_response(streaming_obj)
+        assert streaming_obj.output is None
+
     def test_skips_non_dict_response_output_items(self):
         result = {
             "output": [