Minor Bugfix

Sorry for posting this here, but this seems to be the easiest way to notify the team of the bug.

In ./src/component/security-tweaks/class-prevent-enum-users.php the method maybe_block forces $request as a string. The problem is that there are times when null is passed instead, which creates a critical error.

It seems to specifically happen inside the shield_up method when the filter redirect_canonical fires. I believe this can happen when URL parameters are used on a page that isn’t an actual WordPress page, such as when creating a URL using add_rewrite_endpoint and add_rewrite_rule. Simply allowing null as a value fixes the issue.