Crash while using- before_tts_cb

[Test-isom]

{"message": "Error in _str_synthesis_task\nTraceback (most recent call last):\n File "/root/pythonenv/enve/lib/python3.10/site-packages/livekit/agents/utils/log.py", line 16, in async_fn_logs\n return await fn(*args, **kwargs)\n File "/root/pythonenv/enve/lib/python3.10/site-packages/livekit/agents/voice_assistant/agent_output.py", line 195, in _str_synthesis_task\n handle.tts_forwarder.push_text(transcript)\n File "/root/pythonenv/enve/lib/python3.10/site-packages/livekit/agents/transcription/tts_forwarder.py", line 200, in push_text\n self._text_data.pushed_text += text\nTypeError: can only concatenate str (not "async_generator") to str", "level": "ERROR", "pid": 772990, "job_id": "AJ_owPeUnBxdvK3", "timestamp": "2024-09-09T10:18:21.988046+00:00"}