« MODx Parse Error »

MODx encountered the following error while attempting to parse the requested resource:
« PHP Parse Error »
 
PHP error debug
  Error: Invalid argument supplied for foreach() 
  Error type/ Nr.: Warning - 2 
  File: /usr/home/sites/data/www/pulkovskaja.pihotels.ru/assets/snippets/ditto/classes/ditto.class.inc.php 
  Line: 850 
  Line 850 source: foreach ($modx->documentMap as $null => $document) {  
 
Parser timing
  MySQL: 0.0501 s(3 Requests)
  PHP: 0.0831 s 
  Total: 0.1332 s