fix(prometheus): default to status_code=500 for exceptions without status code

_extract_status_code() returned None when an exception lacked status_code/code
attributes. str(None) became the literal 'None' in Prometheus labels, causing
litellm_proxy_total_requests_metric 4xx/5xx aggregations to not match
litellm_proxy_failed_requests_metric.

Fixes #24224

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

litellm/integrations/prometheus.py

@@ -1448,7 +1448,8 @@ class PrometheusLogger(CustomLogger):
             exception: Exception object to extract status code from directly
 
         Returns:
-            Status code as integer if found, None otherwise
+            Status code as integer if found, 500 when an exception is present
+            but carries no status code attribute, or None when no inputs provided
         """
         status_code = None
 
@@ -1486,6 +1487,14 @@ class PrometheusLogger(CustomLogger):
                     except (ValueError, TypeError):
                         status_code = None
 
+        # If an exception was provided (directly or via kwargs) but no status code
+        # could be extracted, default to 500 — an unclassified server error is still a 5xx.
+        if status_code is None and (
+            exception is not None
+            or (kwargs and kwargs.get("exception") is not None)
+        ):
+            return 500
+
         return status_code
 
     def _is_invalid_api_key_request(

tests/test_litellm/integrations/test_prometheus_status_code_none.py

@@ -39,3 +39,10 @@ def test_extract_status_code_defaults_to_500_for_bare_exception(prometheus_logge
 def test_extract_status_code_returns_none_when_no_exception(prometheus_logger):
     """When no exception is provided at all, should return None."""
     assert prometheus_logger._extract_status_code() is None
+
+
+def test_extract_status_code_defaults_to_500_for_bare_exception_in_kwargs(prometheus_logger):
+    """Bare exception passed through kwargs should also default to 500."""
+    exc = Exception("something broke")
+    result = prometheus_logger._extract_status_code(kwargs={"exception": exc})
+    assert result == 500, f"Expected 500 for bare exception in kwargs, got {result}"