fix: type mismatches and handle nullable values

src/Controller/Traits/AuthenticatedUserTrait.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace App\Controller\Traits;
+
+use App\Entity\User;
+use Symfony\Component\Security\Core\Exception\AuthenticationException;
+
+trait AuthenticatedUserTrait
+{
+    public function getAuthenticatedUser(): User
+    {
+        $user = $this->getUser();
+
+        if (null === $user) {
+            throw new AuthenticationException();
+        }
+
+        return $user;
+    }
+}