Notice: Undefined property: stdClass::$comment_count on thread

When creating a forum thread, on Preview action a "Notice: Undefined property: stdClass::$comment_count" is thrown.

Full error message is:
Notice: Undefined property: stdClass::$comment_count în advanced_forum_preprocess_advanced_forum_topic_header() (linia 452 din /home/bla/public_html/blablabla/sites/all/modules/advanced_forum/includes/theme.inc).

Proposed fix:
Change line 452 from file "theme.inc" from

pager_default_initialize($variables['node']->comment_count, variable_get('comment_default_per_page_' . $variables['node']->type, 50));

to

if(isset($variables['node']->comment_count)) pager_default_initialize($variables['node']->comment_count, variable_get('comment_default_per_page_' . $variables['node']->type, 50));