Build fails if <script> src path doesn't start with a slash

[ngustavo]

Describe the bug

If you move files into an assets folder or any other kind of structure, you must refer to main.js as /assets/main.js. Though, CSS and favicon can be referred as just assets/main.css and assets/favicon.svg.

The issue is that Vite throws this:

The following dependencies are imported but could not be resolved:
    assets/main.js
Are they installed?

But it actually "works" on npm run dev and the script is loaded by the browser as expected. But if you do npm run build, it throws:

[vite]: Rollup failed to resolve import "assets/main.js" from "index.html".

I wonder if this inconsistency happens because Rollup looks into project folder instead of index.html location.

Reproduction

https://stackblitz.com/edit/vitejs-vite-jchmw5?file=index.html&terminal=dev

System Info

System:
  OS: Linux 5.10 Ubuntu 20.04.4 LTS (Focal Fossa)
  CPU: (12) x64 AMD Ryzen 5 1600 Six-Core Processor
  Memory: 11.39 GB / 12.44 GB
  Container: Yes
  Shell: 5.0.17 - /bin/bash
Binaries:
  Node: 17.6.0 - ~/.asdf/installs/nodejs/17.6.0/bin/node
  npm: 8.5.1 - ~/.asdf/plugins/nodejs/shims/npm
npmPackages:
  vite: ^2.9.2 => 2.9.5

Used Package Manager

npm

Logs

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to https://github.com/vuejs/core instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[sapphi-red]

But it actually "works" on npm run dev and the script is loaded by the browser as expected.

To describe more specifically, it only works when you access / or /foo and it does not work with /foo/bar.

Looks like it is supported for relative paths which starts with ..

vite/packages/vite/src/node/server/middlewares/indexHtml.ts

Lines 72 to 91 in 1d468c8

	} else if (
	url.startsWith('.') &&
	originalUrl &&
	originalUrl !== '/' &&
	htmlPath === '/index.html'
	) {
	// #3230 if some request url (localhost:3000/a/b) return to fallback html, the relative assets
	// path will add `/a/` prefix, it will caused 404.
	// rewrite before `./index.js` -> `localhost:3000/a/index.js`.
	// rewrite after `../index.js` -> `localhost:3000/index.js`.
	s.overwrite(
	node.value!.loc.start.offset,
	node.value!.loc.end.offset,
	`"${path.posix.join(
	path.posix.relative(originalUrl, '/'),
	url.slice(1)
	)}"`,
	{ contentOnly: true }
	)
	}

---

For a workaround use ./assets/main.js instead of assets/main.js.