[BUG] Hydrogen broken in Cloudflare production

[jplhomer]

Describe the bug
https://template-default.hydrogen-devs.workers.dev/

The logs we get in Cloudflare don't give us anything, so you have to debug it locally using wrangler dev to see more detailed errors.

tl;dr here is that cloudflare will cancel the request if it finds that you are not planning to return something. i've seen this happen before when promises are involved (spoiler: we have a ton of promises involved).

It seems likely that a change in #758 caused this, though I remember @frandiox had it working in CF before 🤔 Maybe it was some other recent change.

Red herrings to avoid: The Cloudflare Deployment GH Action is currently failing, but it's due to an update in wrangler clearing out stale files. The actual deploy itself is fine.

To Reproduce
I started a branch here: https://github.com/Shopify/hydrogen/tree/jl-wip-cf-debugging

You'll want to run yarn and then inside the template, run wrangler dev (install wrangler first if you don't have it).

• Hydrogen version: current v1.x-2022-07 branch