fix: ws never connects after restarting server if server.hmr.server is set

[sapphi-red]

Description

ws never connected after restarting the server if server.hmr.server is set (e.g. Storybook).

/cc @IanVS

Reproduction

1. Open https://stackblitz.com/github/storybookjs/sandboxes/tree/next/react-vite/default-js/after-storybook?preset=node
2. Open the devtools and select the Network tab (without filter)
3. Wait for storybook starts completely
4. Add .env file in the project root directory
5. See many polling request + failing WS request happening
6. Close the tab quickly (otherwise the tab will crash 😬)

How it happens

If server.hmr.server is not set, when the Vite server restarts, this wsServer becomes a different instance.

vite/packages/vite/src/node/server/ws.ts

Line 107 in 2d8c841

const wsServer = hmrServer || (portsAreCompatible && server)

But since Storybook passes their server to server.hmr.server, even if Vite's server restarted, wsServer is a same instance. Then, the old listener swallows all WebSocket connections and the new listener (started listening after the server restarted) can't handle any requests.

Additional context

Found this bug while looking around storybookjs/storybook#22253.

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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[stackblitz]

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[IanVS]

Oh wow, 2 hours from report to a PR with a bugfix. Thanks so much!

The other part of the Storybook issue that confuses me, is why vite is detecting changes to .env and/or tsconfig.json in the first place. This seems like a reasonable fix to the problem of ws not reconnecting, but do you have any theories on why it happens in the first place?

[sapphi-red]

I don't know why #14126 happens. It didn't happen on my machine (#14043 (comment)). I was trying to reproduce the same situation by running a script that changes the .env file in a infinite while loop, and found this bug 😅.

[IanVS]

I find that it's pretty intermittent. I tend to notice it happening more when changing branches, or installing/removing dependencies. I would have opened an issue a long time ago if I could create a reproduction, but so far haven't been able to. :(

[TNAJanssen]

It feels good (sorry for you guys) that I'm not the only one and not crazy 😆. That said, it even happened to me once on a completely new project, and after restarting the server it went away. For my local machine with my main project, I can't even start the server anymore without ignoring all the file that trigger a restart.

[IanVS]

This seems to be caused by a problem in fsevents: paulmillr/chokidar#1286. It has been fixed, but not yet released there. Patching one line has been reported to prevent the issue for several Storybook users.