Bug: agent crash when tool execution raise exception due to telemetry

[MengJiapeng]

Bug Description

The trace_tool_call function in telemetry.py assumes that function_response_event is always provided. However, when a tool execution raises an exception, function_response_event can be None, causing the code to crash with an AttributeError.

Traceback (most recent call last):
  File "/usr/local/lib/python3.12/site-packages/google/adk/tools/mcp_tool/mcp_session_manager.py", line 163, in wrapper
    return await func(self, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/google/adk/tools/mcp_tool/mcp_tool.py", line 331, in _run_async_impl
    response = await session.call_tool(
               ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mcp/client/session.py", line 377, in call_tool
    result = await self.send_request(
             ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mcp/shared/session.py", line 306, in send_request
    raise McpError(response_or_error.error)
mcp.shared.exceptions.McpError: xxx
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/usr/local/lib/python3.12/site-packages/google/adk/flows/llm_flows/functions.py", line 575, in _execute_single_function_call_async
    function_response_event = await _run_with_trace()
                              ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/google/adk/flows/llm_flows/functions.py", line 523, in _run_with_trace
    raise tool_error
  File "/usr/local/lib/python3.12/site-packages/google/adk/flows/llm_flows/functions.py", line 510, in _run_with_trace
    function_response = await __call_tool_async(
                        ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/google/adk/flows/llm_flows/functions.py", line 936, in __call_tool_async
    return await tool.run_async(args=args, tool_context=tool_context)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/google/adk/tools/mcp_tool/mcp_tool.py", line 286, in run_async
    return await super().run_async(args=args, tool_context=tool_context)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/google/adk/tools/base_authenticated_tool.py", line 94, in run_async
    return await self._run_async_impl(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/google/adk/tools/mcp_tool/mcp_session_manager.py", line 176, in wrapper
    return await func(self, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/google/adk/tools/mcp_tool/mcp_tool.py", line 331, in _run_async_impl
    response = await session.call_tool(
               ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mcp/client/session.py", line 377, in call_tool
    result = await self.send_request(
             ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/mcp/shared/session.py", line 306, in send_request
    raise McpError(response_or_error.error)
mcp.shared.exceptions.McpError: xxx
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/usr/local/lib/python3.12/site-packages/google/adk/a2a/executor/a2a_agent_executor.py", line 155, in execute
    await self._handle_request(context, event_queue)
  File "/usr/local/lib/python3.12/site-packages/google/adk/a2a/executor/a2a_agent_executor.py", line 225, in _handle_request
    async for adk_event in agen:
  File "/usr/local/lib/python3.12/site-packages/veadk/runner.py", line 134, in wrapper
    async for event in func(
  File "/usr/local/lib/python3.12/site-packages/google/adk/runners.py", line 561, in run_async
    async for event in agen:
  File "/usr/local/lib/python3.12/site-packages/google/adk/runners.py", line 549, in _run_with_trace
    async for event in agen:
  File "/usr/local/lib/python3.12/site-packages/google/adk/runners.py", line 778, in _exec_with_plugin
    async for event in agen:
  File "/usr/local/lib/python3.12/site-packages/google/adk/runners.py", line 538, in execute
    async for event in agen:
  File "/usr/local/lib/python3.12/site-packages/google/adk/agents/base_agent.py", line 294, in run_async
    async for event in agen:
  File "/usr/local/lib/python3.12/site-packages/google/adk/agents/llm_agent.py", line 468, in _run_async_impl
    async for event in agen:
  File "/usr/local/lib/python3.12/site-packages/google/adk/flows/llm_flows/base_llm_flow.py", line 427, in run_async
    async for event in agen:
  File "/usr/local/lib/python3.12/site-packages/google/adk/flows/llm_flows/base_llm_flow.py", line 514, in _run_one_step_async
    async for event in agen:
  File "/usr/local/lib/python3.12/site-packages/google/adk/flows/llm_flows/base_llm_flow.py", line 712, in _postprocess_async
    async for event in agen:
  File "/usr/local/lib/python3.12/site-packages/google/adk/flows/llm_flows/base_llm_flow.py", line 830, in _postprocess_handle_function_calls_async
    if function_response_event := await functions.handle_function_calls_async(
                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/google/adk/flows/llm_flows/functions.py", line 342, in handle_function_calls_async
    return await handle_function_call_list_async(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/google/adk/flows/llm_flows/functions.py", line 388, in handle_function_call_list_async
    function_response_events = await asyncio.gather(*tasks)
                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/otel-auto-instrumentation-python/opentelemetry/instrumentation/asyncio/__init__.py", line 299, in trace_coroutine
    return await coro
           ^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/google/adk/flows/llm_flows/functions.py", line 578, in _execute_single_function_call_async
    trace_tool_call(
  File "/usr/local/lib/python3.12/site-packages/veadk/tracing/telemetry/telemetry.py", line 337, in trace_tool_call
    response: ExtractorResponse = attr_extractor(params)
                                  ^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/veadk/tracing/telemetry/attributes/extractors/tool_attributes_extractors.py", line 129, in tool_gen_ai_tool_output
    function_response = params.function_response_event.get_function_responses()[
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'get_function_responses'

Expected Behavior

The tracing code should gracefully handle None values for function_response_event and continue to record available telemetry data (tool name, arguments) without crashing.

Actual Behavior

The code crashes with AttributeError: 'NoneType' object has no attribute 'get_function_responses'

Environment

• Python version: 3.12+
• Package: veadk tracing/telemetry module
• Related to: Tool call tracing and observability