Fix repositories to fetch entity linked to stored object

getSingleResult() replaced by getOneOrNullResult() to\ avoid error being thrown.
Fix naming of properties.

src/Bundle/ChillActivityBundle/Repository/ActivityRepository.php

@@ -102,20 +102,15 @@ class ActivityRepository extends ServiceEntityRepository implements AssociatedEn
         return $qb->getQuery()->getResult();
     }
 
-    /**
-     * @throws NonUniqueResultException
-     * @throws NoResultException
-     */
     public function findAssociatedEntityToStoredObject(StoredObject $storedObject): ?Activity
     {
         $qb = $this->createQueryBuilder('a');
         $query = $qb
-            ->join('a.documents', 'ad')
-            ->join('ad.storedObject', 'so')
-            ->where('so.id = :storedObjectId')
+            ->leftJoin('a.documents', 'ad')
+            ->where('ad.id = :storedObjectId')
             ->setParameter('storedObjectId', $storedObject->getId())
             ->getQuery();
 
-        return $query->getSingleResult();
+        return $query->getOneOrNullResult();
     }
 }