`ssrLoadModule` does not load nested dependency

Describe the bug

Original issue discovered: https://github.com/vitejs/vite/discussions/3464#discussioncomment-807918

I have a vite plugin that make use of the ssr argument in resolveId hook. The main purpose of the plugin is to replace @shopify/polyfills/fetch with @shopify/polyfills/fetch.node when its on the server and @shopify/polyfills/fetch.browser when it is on the client.

This plugins work on the client side, but break when ssrLoadModule is use to load the server entry point.

Some investigations

I have tired to replace @shopify/polyfills/fetch with a random virtual module (ie. virtual:fetch-polyfill) and that work.

Reproduction

Use the branch https://github.com/michenly/app-proving-ground/tree/vite-ssr-dep

Case 1: client side only with a index file

• Run yarn dev
• See the application working with a list displayed in the browser.

Case 2: ssr using vite middleware and ssrLoadModule

• Run yarn run ssr
• See the application fail with the following error

Case 3: same as 2, but using virtual module

• Change @shopify/polyfills/fetch to virtual:fetch-polyfill in both the plugin and the client import in GraphQL.tsx
• Run yarn run ssr
• See the following error which mean the module is broken. But it is loaded on server side.

System Info

Output of npx envinfo --system --npmPackages vite,@vitejs/plugin-vue --binaries --browsers:

System:
    OS: macOS 11.3.1
    CPU: (8) x64 Intel(R) Core(TM) i7-8559U CPU @ 2.70GHz
    Memory: 338.92 MB / 16.00 GB
    Shell: 4.4.23 - /usr/local/bin/bash
  Binaries:
    Node: 16.1.0 - /usr/local/bin/node
    Yarn: 1.22.10 - /usr/local/bin/yarn
    npm: 7.11.2 - /usr/local/bin/npm
    Watchman: 4.9.0 - /usr/local/bin/watchman
  Browsers:
    Chrome: 90.0.4430.212
    Firefox: 72.0.2
    Safari: 14.1
  npmPackages:
    vite: ^2.2.3 => 2.2.3

Used package manager: yarn

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[aleclarson]

It depends. To support the exports field, Vite uses the resolve.exports package, which has a conditions option for deciding which keywords to look for. Note that Vite SSR does not use that package, but this will change with #3951.

[bluwy]

I think the correct solution here is to use exports to load between node and browser, or alias as a workaround for the package. Closing as it seems to be working as intended.