fix: nextjs handler not detected in worker

[ItsWendell]

Fixes #508

Full disclosure (also see issue above):

I don't know why this issue occurs. I just found this fix by experimenting. In the original situation, the worker detects the handler as a 'Getter', but if you use the 'handler' getter the result is undefined, but only on 'cold' boots. In a warm worker the Getter is initialized and it just works. By changing how we export in handler.mjs to a named export, it no longer detects it as a Getter but as a async function and it now works properly on cold boots. If someone could explain why this happens, please do!

[changeset-bot]

🦋 Changeset detected

Latest commit: 6cd43ae

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@opennextjs/cloudflare	Patch

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commit: 6cd43ae

[vicb]

Thank you so much for the patch 🙏

I'm not sure if this is an ESBuild bug or not...
I'll try to reproduce on a simpler example.

But at least this fixes the issue for now 🎉

[vicb]

For ref, once thing that I tried is

      // @ts-expect-error: resolved by wrangler build
      const server = await import("./server-functions/default/handler.mjs");

      while (!server.handler) {
        await new Promise((resolve) => setTimeout(resolve, 0));
      }

It also fixes the issue. Meaning that await does not seem to work as expected...

[ItsWendell]

      while (!server.handler) {

Interesting! Do you know after how many event loops it resolves? Also tests run in wrangler's engine right? Interesting that it didn't catch this. Let me know if you figure out anything more, interesting to see what the core of the wildcard export / import issue is.