In on_chain_error, _persist_resume_trace_context is correctly called before observation.end() (line 868), so the resume key is saved even if end() throws. In the three non-chain handlers (on_retriever_error, on_tool_error, on_llm_error), observation.update().end() is chained and _persist_resume_trace_context is called afterward; if end() throws, the except block is entered without saving the resume key, and the subsequent finally: _reset(run_id) destroys the entire _RootRunState including its re