Update AuditTrailRepository to improve user handling and fix nullable user type in AuditTrail

- Changed `getUser` method in `AuditTrail` to allow null values by updating the return type to `?User`.
- Updated `insert` method in `AuditTrailRepository` to handle nullable users, ensuring the `user_id` parameter is set only when applicable.
- Improved code robustness by adding null-check logic for user assignment in the SQL query.

src/Bundle/ChillMainBundle/Entity/AuditTrail.php

@@ -54,7 +54,7 @@ class AuditTrail
         return $this->id;
     }
 
-    public function getUser(): User
+    public function getUser(): ?User
     {
         return $this->user;
     }

src/Bundle/ChillMainBundle/Repository/AuditTrailRepository.php

@@ -17,7 +17,7 @@ use Doctrine\DBAL\Types\Types;
 use Doctrine\Persistence\ManagerRegistry;
 
 /**
- * @implements ServiceEntityRepository<AuditTrail>
+ * @extends ServiceEntityRepository<AuditTrail>
  */
 class AuditTrailRepository extends ServiceEntityRepository
 {
@@ -48,11 +48,15 @@ class AuditTrailRepository extends ServiceEntityRepository
             ->setParameter('id', $auditTrail->getId())
             ->setParameter('action', $auditTrail->getAction())
             ->setParameter('occured_at', $auditTrail->getOccurredAt(), Types::DATETIMETZ_IMMUTABLE)
-            ->setParameter('user_id', $auditTrail->getUser()?->getId())
+            ->setParameter('user_id', null)
             ->setParameter('description', $auditTrail->getDescription())
             ->setParameter('targets', $auditTrail->getTargets(), Types::JSON)
             ->setParameter('metadata', $auditTrail->getMetadata(), Types::JSON);
 
+        if (null !== $user = $auditTrail->getUser()) {
+            $sql->setParameter('user_id', $user->getId());
+        }
+
         $sql->executeQuery();
     }
 }