I ran into edge case while working on Vitest. Unfortunately I was unable to create minimal reproduction. Reproduction with Vitest: AriPerkkio/vitest@de3dc71

When we add exit listener that calls process.exit inside it, Tinyexec loses stdout from that process. This is similar exit handling as tinylibs/picospinner does.

It seems that subprocess.stdout returned from node:child_process.spawn is closed when subprocess.stderr is read. Here's some logging from Vitest's case:

+ console.log('before', this._streamOut?.closed);
+ // > before false

if (this._streamErr) {
  for await (const chunk of this._streamErr) {
    stderr += chunk.toString();
  }
}

+ console.log('after', this._streamOut?.closed);
+ // > after true

if (this._streamOut) {
  for await (const chunk of this._streamOut) {
    stdout += chunk.toString();
  }
}

To fix these, we'll need to first read stdout.

Replacing tinyexec with node:child_process.execSync works 100% times.