PHP Fatal error: Call to a member function find()

I am getting this error on Line 71 of my code, however the function of this line is executed correctly and it does what I expect it to do.

However, I noticed that my error log is full of these lines:

[09-Dec-2013 14:54:02 UTC] PHP Fatal error: Call to a member function find() on a non-object in /home/sportve/public_html/open_event_common.php on line 71

What I have checked for:

simple_html_dom_parser is already included and this function that Line 71 intend to do is working.

Here is Line 71 of my code:

$content->find('a.openevent', 0)->innertext = '';

so its confusing as to what is causing this error to appear in my error log file?

Edit: here is the full code:

<?php       
    $url = "static/" . $cat_map[$cat]['url'];
    $html = file_get_html($url);
    $content = $html->find('div#event-pane > div#e' . $event_id, 0);
    $content->find('a.openevent', 0)->innertext = '';
    $content->find('h3.lshtitle', 0)->onclick = '';
    $content->find('h3.lshtitle', 0)->tag = 'div';
    $content->find('div.lshtitle', 0)->class = 'ttl';                
?>

Based on the information you’re providing the best and most practical solution is to simply do a check to see if $html and $content is empty or not.

9 times out of 10 when you get a “Call to a member function [whatever the function is] on a non-object” that basically means the object just doesn’t exist. Meaning the variable is empty. Here is your code reworked:

$url = "static/" . $cat_map[$cat]['url'];
if (!empty($url)) {
  $html = file_get_html($url);
  if (!empty($html)) {
    $content = $html->find('div#event-pane > div#e' . $event_id, 0);
    if (!empty($content)) {
      $content->find('a.openevent', 0)->innertext = '';
      $content->find('h3.lshtitle', 0)->onclick = '';
      $content->find('h3.lshtitle', 0)->tag = 'div';
      $content->find('div.lshtitle', 0)->class = 'ttl';
    }
  }
}

Also, I added a check to see if the $url is empty as well.