One of the integration tests is flaky on CI. This is an attempt to "fix"
it.
It has probably something to do with the availability of the resources
provided by GitHub because locally this works flawlessly for 100 runs
straight.
## Test plan
- Once we get 5 consecutive positive runs we van merge it.
- No actual code was changed, only the flaky integration test itself.
<img width="336" height="445" alt="image"
src="https://github.com/user-attachments/assets/bec81687-62f5-4df3-8109-d0aaa4ffbd8a"
/>
## Summary
Under Vite's experimental `bundledDev` mode, the `hotUpdate` hook in
`@tailwindcss/vite` gets called without a `server`. Vite only passes `{
type, file, modules }` here, but the hook loops over
`Object.values(server.environments)`, so editing any file (JS, CSS, or
HTML) throws `TypeError: Cannot read properties of undefined (reading
'environments')` and the dev server build fails.
The fix returns early when `server` is missing. Those environment loops
only look at environments other than the current one, and the
server-level `hot`/`ws` reload channels don't exist in this mode, so
bailing out leaves the classic (non-`bundledDev`) dev path untouched.
Fixes#20378
## Test plan
- Added a unit test that calls `hotUpdate` without a `server` and checks
it doesn't throw. It fails on the current code and passes with the
guard.
- Reproduced with a Vite 8 project using `experimental.bundledDev:
true`: before the change, editing any JS/CSS/HTML file crashed the dev
server; after it, edits work.
- `pnpm run test` and the `@tailwindcss/vite` integration suite both
pass.
[ci-all]
---------
Co-authored-by: Robin Malfait <malfait.robin@gmail.com>
