Add LLM client compaction errors to traces (#9474)

* add llm client errors to traces

* update response json for telemetry

* prevent silent failures and properly log errored responses in streaming path

* remove double logging

---------

Co-authored-by: Amy Guan <amy@letta.com>
Co-authored-by: Kian Jones <kian@letta.com>

letta/llm_api/llm_client_base.py

@@ -161,7 +161,11 @@ class LLMClientBase:
             return
 
         if response_json is None:
-            return
+            if error_msg:
+                response_json = {"error": error_msg, "error_type": error_type}
+            else:
+                logger.warning(f"Skipping telemetry: no response_json or error_msg (call_type={self._telemetry_call_type})")
+                return
 
         try:
             pydantic_actor = self.actor.to_pydantic() if hasattr(self.actor, "to_pydantic") else self.actor