fix(llmobs): guard against None candidates/usage in google_genai extractor

ddtrace/llmobs/_integrations/google_genai.py

@@ -140,7 +140,7 @@ def _extract_output_messages(self, response) -> list[Message]:
         if not response:
             return [Message(content="", role=GOOGLE_GENAI_DEFAULT_MODEL_ROLE)]
         messages = []
-        candidates = _get_attr(response, "candidates", [])
+        candidates = _get_attr(response, "candidates", None) or []
         for candidate in candidates:
             content = _get_attr(candidate, "content", None)
             if not content:

ddtrace/llmobs/_integrations/google_utils.py

@@ -140,7 +140,13 @@ def extract_generation_metrics_google_genai(response) -> dict[str, Any]:
         output_tokens = None
 
     cached_tokens = _get_attr(usage_metadata, "cached_content_token_count", None)
-    total_tokens = _get_attr(usage_metadata, "total_token_count", None) or input_tokens + output_tokens
+    total_token_count = _get_attr(usage_metadata, "total_token_count", None)
+    if total_token_count is not None:
+        total_tokens = total_token_count
+    elif input_tokens is not None and output_tokens is not None:
+        total_tokens = input_tokens + output_tokens
+    else:
+        total_tokens = None
 
     if input_tokens is not None:
         usage[INPUT_TOKENS_METRIC_KEY] = input_tokens

releasenotes/notes/fix-llmobs-google-genai-none-candidates-usage-3f8a1c2d9e4b.yaml

@@ -0,0 +1,8 @@
+---
+fixes:
+  - |
+    LLM Observability: Fix ``Error extracting LLMObs fields`` crash in the google_genai
+    integration when Google GenAI returns partial response objects where ``candidates``
+    or usage metadata token fields are ``None``. This occurred during streaming chunks
+    and safety-filtered responses. Adds None guards before accessing ``candidates`` and
+    token count fields, returning sensible defaults when absent.