don't trigger permissionFailure when it's not needed

(cherry picked from commit a19ed3ed54d4927ef96da8ce96f032dc3b0d897e)

src/Extensions/LeftAndMainSubsites.php

@@ -369,7 +369,7 @@ class LeftAndMainSubsites extends LeftAndMainExtension
             }
 
             // We have not found any accessible section or subsite. User should be denied access.
-            return Security::permissionFailure($this->owner);
+            // This is handled already by LeftAndMain thanks to alternateAccessCheck
         }
 
         // Current site is accessible. Allow through.