Update functions.lib.php (#31461)

Help for developers who doesn't understand the changes in getElementProperties

htdocs/core/lib/functions.lib.php

@@ -13301,6 +13301,7 @@ function fetchObjectByElement($element_id, $element_type, $element_ref = '', $us
 				return $objecttmp;	// returned an object without fetch
 			}
 		} else {
+			dol_syslog($element_prop['classname'].' doesn not exists in '.'/'.$element_prop['classpath'].'/'.$element_prop['classfile'].'.class.php');
 			return -1;
 		}
 	}