src: replace FromJust() with Check() when possible

FromJust() is often used not for its return value, but for its
side-effects. In these cases, Check() exists, and is more clear as to
the intent. From its comment:

  To be used, where the actual value of the Maybe is not needed, like
  Object::Set.

See: https://github.com/nodejs/node/pull/26929/files#r269256335

PR-URL: https://github.com/nodejs/node/pull/27162


Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>