When a package or an install relies on a different user provider, the redirect to the CP login fails if one attempts to access a CP page. Call to a member function preferences() on null

This is because auth()->check() doesn't explicitly check if the authenticated user is a statamic user.

 if (User::current()) {
      $this
          ->mergeDottedUserPreferences()
          ->mergeDottedRolePreferences();
  }