fix: use DEFAULT level and preserve status_message for control-flow exceptions

Instead of setting level=None and clearing status_message for LangGraph
control-flow exceptions, use level="DEFAULT" and keep the status message.
This preserves visibility of interrupt/command events in traces without
marking them as errors. Also applies the same improvement to on_chain_error
for consistency across all four error handlers.

Author: vishnumishra

langfuse/langchain/CallbackHandler.py

@@ -256,7 +256,7 @@ def on_retriever_error(
                 "on_retriever_error", run_id, parent_run_id, error=error
             )
             if any(isinstance(error, t) for t in CONTROL_FLOW_EXCEPTION_TYPES):
-                level = None
+                level = "DEFAULT"
             else:
                 level = "ERROR"
 
@@ -268,7 +268,7 @@ def on_retriever_error(
                         Optional[Literal["DEBUG", "DEFAULT", "WARNING", "ERROR"]],
                         level,
                     ),
-                    status_message=str(error) if level else None,
+                    status_message=str(error),
                     input=kwargs.get("inputs"),
                     cost_details={"total": 0},
                 ).end()
@@ -589,7 +589,7 @@ def on_chain_error(
         try:
             self._log_debug_event("on_chain_error", run_id, parent_run_id, error=error)
             if any(isinstance(error, t) for t in CONTROL_FLOW_EXCEPTION_TYPES):
-                level = None
+                level = "DEFAULT"
             else:
                 level = "ERROR"
 
@@ -601,7 +601,7 @@ def on_chain_error(
                         Optional[Literal["DEBUG", "DEFAULT", "WARNING", "ERROR"]],
                         level,
                     ),
-                    status_message=str(error) if level else None,
+                    status_message=str(error),
                     input=kwargs.get("inputs"),
                     cost_details={"total": 0},
                 ).end()
@@ -812,7 +812,7 @@ def on_tool_error(
         try:
             self._log_debug_event("on_tool_error", run_id, parent_run_id, error=error)
             if any(isinstance(error, t) for t in CONTROL_FLOW_EXCEPTION_TYPES):
-                level = None
+                level = "DEFAULT"
             else:
                 level = "ERROR"
 
@@ -824,7 +824,7 @@ def on_tool_error(
                         Optional[Literal["DEBUG", "DEFAULT", "WARNING", "ERROR"]],
                         level,
                     ),
-                    status_message=str(error) if level else None,
+                    status_message=str(error),
                     input=kwargs.get("inputs"),
                     cost_details={"total": 0},
                 ).end()
@@ -1014,7 +1014,7 @@ def on_llm_error(
         try:
             self._log_debug_event("on_llm_error", run_id, parent_run_id, error=error)
             if any(isinstance(error, t) for t in CONTROL_FLOW_EXCEPTION_TYPES):
-                level = None
+                level = "DEFAULT"
             else:
                 level = "ERROR"
 
@@ -1026,7 +1026,7 @@ def on_llm_error(
                         Optional[Literal["DEBUG", "DEFAULT", "WARNING", "ERROR"]],
                         level,
                     ),
-                    status_message=str(error) if level else None,
+                    status_message=str(error),
                     input=kwargs.get("inputs"),
                     cost_details={"total": 0},
                 ).end()