Ajustement userMerchantStore

Repository/User/UserMerchantStore.php

@@ -41,7 +41,7 @@ class UserMerchantStore extends AbstractStore
     }
 
     // getUserMerchant
-    public function getOneByUser(UserInterface $user, $query = null): UserMerchantInterface
+    public function getOneByUser(UserInterface $user, $query = null): ?UserMerchantInterface
     {
         $query = $this->createDefaultQuery($query);
         $query->filterByUser($user);