lib: remove an unnecessary coverage check

PR-URL: https://github.com/nodejs/node/pull/12023
Fixes: https://github.com/nodejs/node/issues/11445
Refs: f65a48fc


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>