Hot reloads break when loading external CSS

[jameszhou02]

Describe the bug

When launching a gradio app with hot reloading, the initial load works but subsequent changes to CSS files and components using external CSS break the hot reload.

Have you searched existing issues? 🔎

• I have searched and found no existing issues

Reproduction

test.py

import gradio as gr
import os

STYLES_PATH = os.path.join(os.path.dirname(__file__), "styles.css")

with gr.Blocks(
    css=STYLES_PATH,
) as test_demo:
    with gr.Blocks():
        gr.Markdown(
            """
            ## Hello world
            """
        )

if __name__ == "__main__":
    test_demo.launch()

styles.css

html {
  background-color: white;
}

Run command: gradio test.py --demo-name=test_demo

Then change background-color to any other color, or add own CSS.

Screenshot

No response

Logs

Error output (path is just placeholder for where I was testing this python script):

gradio test.py --demo-name=test_demo
Watching: '[path]' '[path]'

Running on local URL:  http://127.0.0.1:7860

To create a public link, set `share=True` in `launch()`.

Changes detected in: [path]/styles.css
Reloading test failed with the following exception:
Traceback (most recent call last):
  File "/Users/james/anaconda3/lib/python3.10/site-packages/gradio/utils.py", line 264, in watchfn
    changed_in_copy = _remove_no_reload_codeblocks(str(changed))
  File "/Users/james/anaconda3/lib/python3.10/site-packages/gradio/utils.py", line 173, in _remove_no_reload_codeblocks
    tree = ast.parse(code)
  File "/Users/james/anaconda3/lib/python3.10/ast.py", line 50, in parse
    return compile(source, filename, mode, flags,
  File "<unknown>", line 1
    html {
         ^
SyntaxError: invalid syntax

### System Info

```shell
gradio version: 4.28.3
python version: 3.10.13

Severity

I can work around it

[jameszhou02]

Same error with python version: 3.11.7

[freddyaboulton]

Thanks @jameszhou02 ! This should be a straightforward fix. We need to skip lines 264 to 272 in this file if the source file that changed is not a python file.

Would you like to open a PR?

[jameszhou02]

On it!

[jameszhou02]

Submitted a PR that's passing all tests here: #8194

Was running into local issues when messing w/ hot-reloading but they're really minor. Essentially changes are detected but when the hot reload occurs seems to be dynamic. Here's a video of what was happening---wasn't sure if this is the intended behavior because it seems inconsistent.

Screen.Recording.2024-05-01.at.7.46.20.PM.mov

[freddyaboulton]

Hmm I think that may be an unrelated bug. Will review your PR shortly

[freddyaboulton]

Hi @jameszhou02 , that issue you saw where the textbox value was not updated in reload mode has been fixed in #8227