[hydrogen] Polyfill Oxygen global in Hydrogen

[frandiox]

Related Issues

It's currently not possible to access environment variables in Hydrogen projects deployed to Vercel. The reason is that Hydrogen currently relies on a global Oxygen.env that needs to be polyfilled in the platform. This PR adds the global object using process.env, which is mentioned in the docs as the way to access environment variables in Edge Functions.

@TooTallNate Can you double check if this is correct? I'm not quite sure process.env is the right thing here even if it's mentioned in the docs 😅

📋 Checklist

Tests

• The code changed/added as part of this PR has been covered with tests
• All tests pass locally with yarn test-unit

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[EndangeredMassa]

Can you also add a test that shows the environment variables being used? You can make a new fixture, set env vars, make sure they are used in the fixture app somewhere, then leverage a vercel.json probe to test for that value.

If not, no worries! We can add a test for this.

[EndangeredMassa]

We may want to do globalThis changes in one clear place up top, like:

Object.assign(globalThis, {
  // ReadableStream is bugged in Vercel Edge, overwrite with polyfill
  ReadableStream,

  // Hydrogen exposes env vars through `Oxygen.env`
  Oxygen: {
    env: process.env
  }
});

[cb1kenobi]

I second this idea. Global is global and it's best outside of a function.

[mperreux]

👋 hey I made this change here #8496 if you want to take a look

[styfle]

Closing in favor of #8496