fix hinting and tests for L10 and PHP8

app/Http/Middleware/Authenticate.php

@@ -10,11 +10,14 @@ class Authenticate extends Middleware
      * Get the path the user should be redirected to when they are not authenticated.
      *
      * @param  mixed $request Request.
+     * @return ?string
      */
     protected function redirectTo(mixed $request): ?string
     {
         if ($request->expectsJson() === false) {
             return route('login');
         }
+
+        return null;
     }
 }