On the Laravel News site they highlight a change in the way that the "gates" handling works in the v5.7 release of the popular framework. In this change you can now allow "guest" users into certain parts of your system.
In Laravel 5.6 and below authorization gates and policies automatically return false for unauthenticated users. New in Laravel 5.7, you can now allow guests to go through authorization checks by using a nullable type-hint or setting the default value as null:
[...] By using a nullable type hint the $user variable will be null when a guest user is passed to the gate, and you can then make decisions about authorizing the action. If you allow nullable types and return true, then the guest will have authorization.
The post includes a code snippet showing how to put it to use and the resulting 403 page they would get otherwise. You can find out more about other new features of Laravel v5.7 in this other article.