phpstan level 1 errors reduction

homepage/participo/attributer.php

@@ -1,4 +1,6 @@
 <?php
+/** @var array $CONFIG basic configurations (defined via bootstraping) */
+/** @var array $SECRETS passwords and other stuff worth of protection (defined via bootstraping) */
 require_once "bootstrap.php";
 
 // libraries
@@ -143,7 +145,7 @@ function withdrawUsersAttribute($anUserId, $anAttributeId, $limit = null)
         print "Error!: " .
             $db_error->getMessage() .
             "<br/>queryString: " .
-            $queryString .
+            ($queryString ?? "<invalid>") .
             "<br />";
         var_dump($bindArray);
     }