AttributeError in Gradio Web Server: 'list' object has no attribute 'text_models'

Nobody has claimed this yet.

## Description:
I followed the instructions to run the WebGUI service in single-model mode by launching the controller, model workers, and Gradio web server. However, when I opened the website, the Gradio web server triggered an error, and the website failed to render correctly.

## Error Message and Screenshot:

```
2024-10-22 21:45:16 | ERROR | stderr | Traceback (most recent call last):
2024-10-22 21:45:16 | ERROR | stderr | File "/home/patrickwu/miniconda3/envs/fastchat/lib/python3.10/site-packages/gradio/queueing.py", line 624, in process_events
2024-10-22 21:45:16 | ERROR | stderr | response = await route_utils.call_process_api(
2024-10-22 21:45:16 | ERROR | stderr | File "/home/patrickwu/miniconda3/envs/fastchat/lib/python3.10/site-packages/gradio/route_utils.py", line 323, in call_process_api
2024-10-22 21:45:16 | ERROR | stderr | output = await app.get_blocks().process_api(
2024-10-22 21:45:16 | ERROR | stderr | File "/home/patrickwu/miniconda3/envs/fastchat/lib/python3.10/site-packages/gradio/blocks.py", line 2018, in process_api
2024-10-22 21:45:16 | ERROR | stderr | result = await self.call_function(
2024-10-22 21:45:16 | ERROR | stderr | File "/home/patrickwu/miniconda3/envs/fastchat/lib/python3.10/site-packages/gradio/blocks.py", line 1567, in call_function
2024-10-22 21:45:16 | ERROR | stderr | prediction = await anyio.to_thread.run_sync( # type: ignore
2024-10-22 21:45:16 | ERROR | stderr | File "/home/patrickwu/.local/lib/python3.10/site-packages/anyio/to_thread.py", line 56, in run_sync
2024-10-22 21:45:16 | ERROR | stderr | return await get_async_backend().run_sync_in_worker_thread(
2024-10-22 21:45:16 | ERROR | stderr | File "/home/patrickwu/.local/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 2144, in run_sync_in_worker_thread
2024-10-22 21:45:16 | ERROR | stderr | return await future
2024-10-22 21:45:16 | ERROR | stderr | File "/home/patrickwu/.local/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 851, in run
2024-10-22 21:45:16 | ERROR | stderr | result = context.run(func, *args)
2024-10-22 21:45:16 | ERROR | stderr | File "/home/patrickwu/miniconda3/envs/fastchat/lib/python3.10/site-packages/gradio/utils.py", line 846, in wrapper
2024-10-22 21:45:16 | ERROR | stderr | response = f(*args, **kwargs)
2024-10-22 21:45:16 | ERROR | stderr | File "/home/patrickwu/FastChat/fastchat/serve/gradio_web_server.py", line 263, in load_demo
2024-10-22 21:45:16 | ERROR | stderr | return load_demo_single(models, url_params)
2024-10-22 21:45:16 | ERROR | stderr | File "/home/patrickwu/FastChat/fastchat/serve/gradio_web_server.py", line 235, in load_demo_single
2024-10-22 21:45:16 | ERROR | stderr | models = context.text_models
2024-10-22 21:45:16 | ERROR | stderr | AttributeError: 'list' object has no attribute 'text_models'
```

## Potential Issue:
In the `load_demo` function, we're passing a list as the first argument to `load_demo_single(models, url_params)`. However, it appears that this argument should be a `Context` object, not a list. The error occurs because the list object doesn't have the `text_models` attribute, which causes the `AttributeError`.

## Steps to Reproduce:
1. Follow the instructions to install the package and run the WebGUI service in single-model mode.
2. Launch the controller, model workers, and Gradio web server.
3. Open the website and observe the error.

Start in fastchat/serve/gradio_web_server.py, especially load_demo and load_demo_single around the reported lines. Reproduce single-model mode by launching the controller, model worker, and Gradio web server, then inspect the value passed between these entry points. Done means the website renders in single-model mode without the reported AttributeError.

Written by the indexing model from the issue text.