src: use Check() instead of FromJust in environment

This commit replaces FromJust() calls with Check() in places where the
value that FromJust() returns is not used.

PR-URL: https://github.com/nodejs/node/pull/33706


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