use vad stream in stt stream sometimes got exception not set at the beginning

[DeoLeung]

https://github.com/livekit/agents/blob/main/livekit-agents/livekit/agents/vad.py#L164

Error in send_task
Traceback (most recent call last):
  File "ib/python3.12/site-packages/livekit/agents/vad.py", line 162, in __anext__
    val = await self._event_aiter.__anext__()
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
StopAsyncIteration

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "lib/python3.12/site-packages/livekit/agents/utils/log.py", line 16, in async_fn_logs
    return await fn(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/sttv3.py", line 289, in send_task
    async for event in self._vad_stream:
  File "ib/python3.12/site-packages/livekit/agents/vad.py", line 164, in __anext__
    if not self._task.cancelled() and (exc := self._task.exception()):
                                              ^^^^^^^^^^^^^^^^^^^^^^
asyncio.exceptions.InvalidStateError: Exception is not set.

i'm manually iterating the vad stream in my stt module, but occationally at the start will get this error, any idea of how to avoid this?