[12.x] Nullsafe operator (#10304)

* Nullsafe operator

* Update telescope.md

* Update telescope.md

---------

Co-authored-by: Taylor Otwell <[email protected]>

Author: AhmedAlaa4611

telescope.md

@@ -475,7 +475,9 @@ public function register(): void
     // ...
 
     Telescope::avatar(function (?string $id, ?string $email) {
-        return '/avatars/'.User::find($id)->avatar_path;
+        return ! is_null($id)
+            ? '/avatars/'.User::find($id)->avatar_path
+            : '/generic-avatar.jpg';
     });
 }
 ```