alias is handled before attemptnig to find the module, breaking any usages with @ alias

[xsjcTony]

Environment

unbuild: v3.0.0-rc.11
Node.js: v20.18.1

Reproduction

https://github.com/xsjcTony/unocss-preset-animations
If unbuild's version is upgraded to v3.0.0-rc.2 or greater, externals won't work as expected due to this issue.

Describe the bug

Because of the implementation here https://github.com/unjs/unbuild/blob/main/src/builders/rollup/utils.ts#L44-L54 simply replace all alias keys, normal usages like @ will break.

E.g. when I'm trying to alias my root as @, then I'll have something like

import { foo } from '@/bar'

But I can also have something like

import { definePreset } from '@unocss/core`

This will break straight away with setting

alias: {
  '@': fileURLToPath(new URL('src', import.meta.url))
}

Resulting in something like

// Original
@unocss/core
// After replacing
C:\Dev\personal-projects\unocss-preset-animations\srcunocss/core

Hence even if I set @unocss/core in externals, it will still be inlined.

---

Solution:

I think it should attempt to find the module first, before parsing alias, giving it a chance to find the correct package straight away.

Additional context

😂Every package start with @ just breaks
@jridgewell/sourcemap-codec
->
C:\Dev\personal-projects\unocss-preset-animations\srcjridgewell/sourcemap-codec

Logs

No response

[pi0]

We should fix the alias issue but there will be always issues with @ aliases. ~ is much safer option I suggest also you can use @/ or @[id] aliases which are more explicit and won't conflict.