I'm getting a error displayed right at the top of the page

I'm getting a error displayed right at the top of the page ... and I just submitted the site to the client for review. Everything was fine, then I installed Yoast and the additional plugin SEO Extended where you can change titles for the browser tab. I have deleted these, but my problem persist.

My url: http://tinyurl.com/mcrqhua

The error mentions line 39 ...

Here's the code from that file:
------------------------------------
<?php
/*
Plugin Name: Breadcrumb NavXT Paged Title Extensions
Plugin URI: http://mtekk.us/code/breadcrumb-navxt/
Description: Replaces the paged breadcrumb with a custom title. For details on how to use this plugin visit Breadcrumb NavXT.
Version: 1.0.0
Author: John Havlik
Author URI: http://mtekk.us/
*/
/* Copyright 2011 John Havlik (email : mtekkmonkey@gmail.com)

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
//Add in our action hook to run after the trail has been filled
add_action('bcn_after_fill', 'bcnext_cust_paged');
/**
* We're going to pop off the paged breadcrumb and add in our own thing
*
* @param object $trail the breadcrumb_trail object after it has been filled
*/
function bcnext_cust_paged($trail)
{
//Only run whe on a single page/post/CPT
if(is_singular())
{
//Check to see if it is a paged type
if(in_array('paged', $trail->trail[0]->type))
{
//Let's change the title
$trail->trail[0]->set_title(bcnext_cust_title($trail->trail[0]->get_title()));
}
}
}
/**
* Returns the custom paged title
*/
function bcnext_cust_title($current_title)
{
global $page, $post;
$pages = explode('<!--nextpage-->', $post->post_content);
$title = $current_title;
$part_content = $pages[$page-1];
$has_part_title = strpos($part_content, '<!--pagetitle:');
if(0 === $has_part_title)
{
$end = strpos($part_content, '-->');
$title = trim(str_replace('<!--pagetitle:', '', substr($part_content, 0, $end)));
}
$title = isset($title) && (strlen($title) > 0) ? $title : 'First';
return $title;
}