minor #10698 Less code (MohamedElKadaoui)

This PR was submitted for the 3.4 branch but it was merged into the 2.8 branch instead (closes #10698).

Discussion
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Less code

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Commits
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8e6b9f6 Less code

Author: javiereguiluz

doctrine/associations.rst

@@ -375,11 +375,7 @@ following method to the ``ProductRepository`` class::
                 WHERE p.id = :id'
             )->setParameter('id', $productId);
 
-        try {
-            return $query->getSingleResult();
-        } catch (\Doctrine\ORM\NoResultException $exception) {
-            return null;
-        }
+        return $query->getOneOrNullResult();
     }
 
 Now, you can use this method in your controller to query for a ``Product``