As I see, from qa-page-question.php line 254 you are calling the function:
$qa_content['q_view']['c_form']=qa_page_q_close_q_form($qa_content, $question, 'close', @$closein, @$closeerrors);
However, nowhere $closein is defined? (which gets $in in qa-page-question-post.php, above.