Fatal exception

$posts_ary = array(
        'SELECT'    => 'p.*, t.*, u.username,
                         u.user_colour, p.bbcode_bitfield ',
        'FROM'      => array(
            POSTS_TABLE     => 'p',
        ),
        'LEFT_JOIN' => array(
            array(
                'FROM'  => array(USERS_TABLE => 'u'),
                'ON'    => 'u.user_id = p.poster_id'
            ),
            array(
                'FROM'  => array(TOPICS_TABLE => 't'),
                'ON'    => 'p.topic_id = t.topic_id'
            ),
        ),
        'WHERE'     =>  'p.post_id = ' . $post_id_article ,
        'ORDER_BY'  => 'p.post_id DESC',
    );
 
$sql = 'SELECT *
    FROM ' . ATTACHMENTS_TABLE . '
    WHERE post_msg_id = '.$post_id_article.'
            AND in_message = 0
    ORDER BY filetime DESC, post_msg_id ASC';
$result = $db->sql_query($sql);
$attachments = array();
while ($row = $db->sql_fetchrow($result))
{
    $attachments[$post_id_article][] = $row;
}
 
$db->sql_freeresult($result);
 
$posts = $db->sql_build_query('SELECT', $posts_ary);
$search_limit = 1;
$posts_result = $db->sql_query_limit($posts, $search_limit);
 
if($posts_row = $db->sql_fetchrow($posts_result))
{
    $topic_title = $posts_row['topic_title'];
    $post_author = get_username_string('full',
                      $posts_row['poster_id'],
                      $posts_row['username'],
                      $posts_row['user_colour']);
    $post_date = $user->format_date($posts_row['post_time']);
    $post_link = append_sid("{$phpbb_root_path}viewtopic.$phpEx",
                  'f=' .$posts_row['forum_id'] .
                  '&t=' . $posts_row['topic_id'] .
                  '&p=' . $posts_row['post_id']) . '#p' .
                   $posts_row['post_id'];
    $bbcode_bitfield = $posts_row['bbcode_bitfield'];
 
    $post_text = nl2br($posts_row['post_text']);
 
    $bbcode = new bbcode(base64_encode($bbcode_bitfield));
    $bbcode->bbcode_second_pass($post_text,
                                $posts_row['bbcode_uid'],
                                $posts_row['bbcode_bitfield']);
 
    $post_text = smiley_text($post_text);
 
    parse_attachments($forum_id,
                        $post_text,$attachments[$post_id_article],
                        $update_count);
 
    echo $topic_title."<br>";
    echo $post_text;
}