Proxy fixes mpl

[maxtheman]

📝 Summary

fixes this bug that happens on closed when the web socket is connected that wasn't caught in the previous PR:

  File "/Users/max/Documents/causal_quartets/.venv/lib/python3.12/site-packages/uvicorn/protocols/websockets/websockets_impl.py", line 358, in asgi_send
    raise RuntimeError(msg % message_type)
RuntimeError: Unexpected ASGI message 'websocket.close', after sending 'websocket.close' or response already completed.

🔍 Description of Changes

It simply checks the state of the WebSocket before trying to close it.

📋 Checklist

• [x] I have read the contributor guidelines.
• [x] For large changes, or changes that affect the public API: this change was discussed or approved through an issue, on Discord, or the community discussions (Please provide a link if applicable).
• [x] I have added tests for the changes made.
• [x] I have run the code and verified that it works as expected.

📜 Reviewers

@mscolnick

[vercel[bot]]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
marimo-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Nov 19, 2024 1:50am
marimo-storybook	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Nov 19, 2024 1:50am

[mscolnick]

thank you! theres going to be some typing errors, but ill fix this for you