Update langfuse/openai.py

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

Author: hassiebp

langfuse/openai.py

@@ -665,9 +665,10 @@ def _get_langfuse_data_from_default_response(resource: OpenAiDefinition, respons
     elif resource.object == "Responses":
         output = response.get("output", {})
 
-        if len(output) > 1:
+        if not isinstance(output, list):
+            completion = output
+        elif len(output) > 1:
             completion = output
-
         elif len(output) == 1:
             completion = output[0]