fix(js): possible race condition in the wrappers

[AlexCannonball]

Hello,

I've checked the recent test failures from #537 and #530:

Test install on ubuntu-latest / Node lts/*

  npm install --omit=dev --no-audit --no-fund
  # Verify local binaries via npx (using --no-install to force local check)
  npx --no-install protolint version
  npx --no-install protoc-gen-protolint version
  shell: /usr/bin/bash -e {0}

> protolint@0.47.4 postinstall
> node postinstall.js

protolint-install: Fetching protolint executable from https://github.com/yoheimuta/protolint/releases/download/v0.47.4/protolint_0.47.4_linux_amd64.tar.gz
protolint-install: Protolint installed successfully.

added 2 packages in 2s
protolint version 0.47.4(2f86d18)
Error: Process completed with exit code 1.

Test install on ubuntu-latest / Node 20

  npm install --omit=dev --no-audit --no-fund
  # Verify local binaries via npx (using --no-install to force local check)
  npx --no-install protolint version
  npx --no-install protoc-gen-protolint version
  shell: /usr/bin/bash -e {0}

> protolint@0.47.4 postinstall
> node postinstall.js

protolint-install: Fetching protolint executable from https://github.com/yoheimuta/protolint/releases/download/v0.47.4/protolint_0.47.4_linux_amd64.tar.gz
protolint-install: Protolint installed successfully.

added 2 packages in 2s
protolint version 0.47.4(2f86d18)
Error: Process completed with exit code 1.

Test install on windows-latest / Node 20

  npm install --omit=dev --no-audit --no-fund
  # Verify local binaries via npx (using --no-install to force local check)
  npx --no-install protolint version
  npx --no-install protoc-gen-protolint version
  shell: C:\Program Files\PowerShell\7\pwsh.EXE -command ". '{0}'"

> protolint@0.47.4 postinstall
> node postinstall.js

protolint-install: Fetching protolint executable from https://github.com/yoheimuta/protolint/releases/download/v0.47.4/protolint_0.47.4_windows_amd64.tar.gz
protolint-install: Protolint installed successfully.

added 2 packages in 3s
protolint version 0.47.4(2f86d18)
Error: Process completed with exit code 1.

Except failing protoc-gen-protolint version in local install case, it doesn't seem to have a consistent pattern so far.

Gemini tells that adding a top-level await may fix a possible race condition when the Node main process cleanup happens before close event listener completes its job.

This sounds reasonable and the top level await shouldn't make it worse.

[yoheimuta]

Thank you for the fix.