no issue - fix null being written with a value in string pattern anonymizer

Author: pounard

src/Anonymization/Anonymizer/Core/StringPatternAnonymizer.php

@@ -155,7 +155,9 @@ public function createAnonymizeExpression(Update $update): Expression
             }
         }
 
-        return $expr->concat(...$expressions);
+        return $this->getSetIfNotNullExpression(
+            $expr->concat(...$expressions),
+        );
     }
 
     #[\Override]