fix(oai): fixing a bug when not using the OpenAIWrapper by making rate limiter config optional. (#4066)

Co-authored-by: Joel Klaverkamp <joel.klaverkamp@upfeat.com>

autogen/oai/client.py

@@ -1069,7 +1069,7 @@ class OpenAIWrapper:
 
     def _throttle_api_calls(self, idx: int) -> None:
         """Rate limit api calls."""
-        if self._rate_limiters[idx]:
+        if idx < len(self._rate_limiters) and self._rate_limiters[idx]:
             limiter = self._rate_limiters[idx]
 
             assert limiter is not None