prevent empty support messages in help module (Fixes: #3697)

Florian Schaal

2016-05-26 52a8e7e2f53b23f41b40aa5bc5b35f338aaec3dd

 interface/lib/classes/listform.inc.php

@@ -563,7 +563,7 @@
               break;

            case 'DATE':
               if($record[$key] != '' && $record[$key] != '0000-00-00') {
               if($record[$key] != '' && !is_null($record[$key]) && $record[$key] != '0000-00-00') {
                  $record[$key] = $record[$key];
               }
               break;