test:unit fails with UnhandledPromiseRejection "Symbol(kExitCode)" on Node.js 20/22/24

[ledsun]

Summary

rake npm:ruby-head-wasm-wasi:check currently fails during test:unit with an unhandled promise rejection whose reason is "Symbol(kExitCode)".

This looks separate from #314.
The original options.version issue is already fixed on current main, but the test suite still fails later with a different error.

Reproduction

rake npm:ruby-head-wasm-wasi:check

It can also be reproduced more directly with:

cd packages/npm-packages/ruby-wasm-wasi
RUBY_NPM_PACKAGE_ROOT=../ruby-head-wasm-wasi ./tools/run-test-unit.mjs

Observed on

• Node.js 20.20.1
• Node.js 22.11.0
• Node.js 24.14.0

Current error

For example on Node.js 24.14.0:

(node:8538) ExperimentalWarning: WASI is an experimental feature and might change at any time
(Use `node --trace-warnings ...` to show where the warning was created)
node:internal/process/promises:392
      new UnhandledPromiseRejection(reason);
      ^

UnhandledPromiseRejection: This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). The promise rejected with the reason "Symbol(kExitCode)".
    at throwUnhandledRejectionsMode (node:internal/process/promises:392:7)
    at processPromiseRejections (node:internal/process/promises:475:17)
    at process.processTicksAndRejections (node:internal/process/task_queues:105:32) {
  code: 'ERR_UNHANDLED_REJECTION'
}

Node.js v24.14.0