feat!: remove ssr proxy for externalized modules

[bluwy]

Description

Implements solution 2 of #14503

SSR-externalized module are now not handled with special .default and .__esModule handling access in dev, matching the behaviour in prod. Non-externalized modules stay the same, they are already ESM after all.

The main change is to not call proxyESM. The rest are created for better error messages to identify how to fix it.

I also added legacy.proxySsrExternalModules to return to the previous behaviour.

Additional context

See #14503 for more context.

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the PR Title Convention.
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[benmccann]

I've seen users struggle with knowing that they sometimes have to do import * as pkg. I wonder if there's some sort of warning we could print in dev mode when they don't do this in order to guide them towards the correct solution?

[bluwy]

I've seen users struggle with knowing that they sometimes have to do import * as pkg. I wonder if there's some sort of warning we could print in dev mode when they don't do this in order to guide them towards the correct solution?

There's actually an instance of this in Vite you can test out.

vite/playground/ssr-deps/src/app.js

Lines 24 to 25 in b868033

	import * as optimizedWithNestedExternal from '@vitejs/test-optimized-with-nested-external'
	import * as optimizedCjsWithNestedExternal from '@vitejs/test-optimized-cjs-with-nested-external'

Without the * as it reports (Vite emulated error):

SyntaxError: The requested module '@vitejs/test-optimized-with-nested-external' does not provide an export named 'default'
    at Object.get (file:///Users/bjorn/Work/oss/vite/packages/vite/dist/node/chunks/dep-da74c78d.js:56763:23)
    at render (/Users/bjorn/Work/oss/vite/playground/ssr-deps/src/app.js:74:46)
    at async file:///Users/bjorn/Work/oss/vite/playground/ssr-deps/server.js:98:23

We can definitely add more hints/suggestions here, but I think we can improve on that in a later PR.

[benmccann]

Yeah, I wasn't sure if users know how to fix it though. The error message could be tweaked a bit to include a solution like The requested module '@vitejs/test-optimized-with-nested-external' does not provide an export named 'default'. Try importing with: import * as pkg from '@vitejs/test-optimized-with-nested-external'

[bluwy]

I think we should wait to see how users are often hitting this before adding the hints. I'm afraid to add some suggestions that could be misleading otherwise. Plus there's a lot of resource for that error message on the web that they should be able to find different solutions to what they're hitting.

[sapphi-red]

LGTM (If the github discussion link is updated later)

[sapphi-red]

It would be nice to add this to docs/guide/migration.md.

[bluwy]

/ecosystem-ci run

[vite-ecosystem-ci]

📝 Ran ecosystem CI: Open

suite	result
analogjs	✅ success
astro	✅ success
histoire	✅ success
ladle	✅ success
laravel	✅ success
marko	❌ failure
nuxt	✅ success
nx	✅ success
previewjs	✅ success
qwik	❌ failure
rakkas	❌ failure
sveltekit	✅ success
unocss	❌ failure
vike	✅ success
vite-plugin-pwa	✅ success
vite-plugin-react	✅ success
vite-plugin-react-pages	✅ success
vite-plugin-react-swc	✅ success
vite-plugin-svelte	✅ success
vite-plugin-vue	✅ success
vite-setup-catalogue	✅ success
vitepress	✅ success
vitest	✅ success