Example on using LlamaIndex stream_chat()

The Streamlit docs on creating a streaming chatbot show the following example:

for response in client.chat.completions.create(
        model=st.session_state["openai_model"],
        messages=[{"role": m["role"], "content": m["content"]} for m in st.session_state.messages],
        stream=True,
    ):

...but there is no example (that I can find) of creating a streaming chat engine from an index object as shown in the LlamaIndex examples:

chat_engine = index.as_chat_engine()
streaming_response = chat_engine.stream_chat("Tell me a joke.")
for token in streaming_response.response_gen:
    print(token, end="")

If I try to use chat_engine.stream_chat with the for response in client.chat.completions.create() pattern as shown in the Streamlit docs, I get the following error RuntimeError: There is no current event loop in thread 'ScriptRunner.scriptThread'.

An example traceback when trying to simply use:

if st.session_state.messages[-1]["role"] != "assistant":
    with st.chat_message("assistant"):
        message_placeholder = st.empty()
        full_response = ""
        for token in st.session_state.chat_engine.stream_chat(prompt):
            print(token)
        message_placeholder.markdown(full_response)
        st.session_state.messages.append({"role": "assistant", "content": full_response})

As in the Streamlit docs on creating a streaming chatbot.

Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/streamlit/runtime/scriptrunner/script_runner.py", line 534, in _run_script
    exec(code, module.__dict__)
  File "/workspaces/gcp_llm/app.py", line 67, in <module>
    for token in st.session_state.chat_engine.stream_chat(prompt):
  File "/usr/local/lib/python3.9/site-packages/llama_index/callbacks/utils.py", line 39, in wrapper
    return func(self, *args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/llama_index/agent/openai_agent.py", line 444, in stream_chat
    chat_response = self._chat(
  File "/usr/local/lib/python3.9/site-packages/llama_index/agent/openai_agent.py", line 330, in _chat
    agent_chat_response = self._get_agent_response(mode=mode, **llm_chat_kwargs)
  File "/usr/local/lib/python3.9/site-packages/llama_index/agent/openai_agent.py", line 295, in _get_agent_response
    return self._get_stream_ai_response(**llm_chat_kwargs)
  File "/usr/local/lib/python3.9/site-packages/llama_index/agent/openai_agent.py", line 196, in _get_stream_ai_response
    chat_stream_response = StreamingAgentChatResponse(
  File "<string>", line 10, in __init__
  File "/usr/local/lib/python3.9/asyncio/queues.py", line 36, in __init__
    self._loop = events.get_event_loop()
  File "/usr/local/lib/python3.9/asyncio/events.py", line 642, in get_event_loop
    raise RuntimeError('There is no current event loop in thread %r.'
RuntimeError: There is no current event loop in thread 'ScriptRunner.scriptThread'.

streamlit / docs

Example on using LlamaIndex stream_chat() #885