src: do not unnecessarily re-assign uv handle data

a555be2e re-assigned `async_.data` to indicate success
or failure of the constructor. As the `HandleWrap` implementation
uses that field to access the `HandleWrap` instance from the
libuv handle, this introduced two issues:

- It implicitly assumed that casting
  `MessagePort*` → `void*` → `HandleWrap*` would be valid.
- It made the `HandleWrap::OnClose()` function fail with a
  `nullptr` dereference if the constructor did fail.

In particular, the second issue made
test/parallel/test-worker-cleanexit-with-moduleload.js` crash at
least once in CI.

Since re-assigning `async_.data` isn’t actually necessary here
(only a leftover from earlier versions of that commit), fix this by
using a local variable instead, and add a `CHECK` that provides better
error messages for this type of issue in the future.

Refs: https://github.com/nodejs/node/pull/31605

PR-URL: https://github.com/nodejs/node/pull/31696


Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>