MQE-588: CreatedData should throw Error/Warning when undefined data is returned

- prevent printing in unit phase

Author: jilu1

dev/tests/unit/Magento/FunctionalTestFramework/DataGenerator/Handlers/PersistedObjectHandlerTest.php

@@ -433,7 +433,7 @@ public function testRetrieveEntityInValidField($name, $key, $value, $type, $scop
 
         // validate log statement
         TestLoggingUtil::getInstance()->validateMockLogStatement(
-            "warning",
+            'warning',
             $warnMsg,
             []
         );