fix: prevent hang when process is overwritten

[AriPerkkio]

• Fixes vitest hangs with stubbed process vitest-dev/vitest#5390

[hi-ogawa]

Looks good!

[Aslemammad]

I assume this stabilizes the process and keeps the same reference, correct?

[AriPerkkio]

Yes, we will preserve the original process methods in the module scope. The file that is loaded later may overwrite globals:

tinypool/src/entry/process.ts

Lines 35 to 36 in 6ca7bb4

	if (filename !== null) {
	await getHandler(filename, name)

So basically:

process.on("message", async (msg) => {
  const originalSend = process.send.bind(process);

  await import(msg.filename); // Contains globalThis.process = Mock;

  process.send(response);
  //      ^^^^ send is not a function

  originalSend(response);
  // ^^ works
})

birpc has similar implementation: https://github.com/antfu/birpc/blob/72510536cedb301953e0550d884667804d7268d0/src/index.ts#L145-L147

[Aslemammad]

LGTM! Feel free to merge.