Cache error

[SSSV]

I deleted a few empty categories and I'm suddenly seeing this error on my site:

Catchable fatal error: Object of class WP_Error could not be converted to string in /home/content/l/i/s/lisaholley/html/redesign/wp-includes/formatting.php on line 3042

The following is the code on line 3042 in formatting.php:
$url = preg_replace('|[^a-z0-9-~+_.?#=!&;,/:%@$|*\'()\x80-\xff]|i', '', $url);

I've had to completely deactivate the plugin to resurrect the site below that widget. Any ideas? This isn't something I'm familiar with. Thanks!

Full code:
/**

• Checks and cleans a URL.
  *

• A number of characters are removed from the URL. If the URL is for displaying

• (the default behaviour) ampersands are also replaced. The 'clean_url' filter

• is applied to the returned cleaned URL.
  *

• @SInCE 2.8.0
  *

• @param string $url The URL to be cleaned.

• @param array $protocols Optional. An array of acceptable protocols.

•  Defaults to 'http', 'https', 'ftp', 'ftps', 'mailto', 'news', 'irc', 'gopher', 'nntp', 'feed', 'telnet', 'mms', 'rtsp', 'svn' if not set.
  

• @param string $_context Private. Use esc_url_raw() for database usage.

• @return string The cleaned $url after the 'clean_url' filter is applied.
  */
  function esc_url( $url, $protocols = null, $_context = 'display' ) {
  $original_url = $url;

  if ( '' == $url )
  return $url;
  $url = preg_replace('|[^a-z0-9-~+_.?#=!&;,/:%@$|_\'()\x80-\xff]|i', '', $url);
  $strip = array('%0d', '%0a', '%0D', '%0A');
  $url = deep_replace($strip, $url);
  $url = str_replace(';//', '://', $url);
  / If the URL doesn't appear to contain a scheme, we

  • presume it needs http:// appended (unless a relative
  • link starting with /, # or ? or a php file).
    */
    if ( strpos($url, ':') === false && ! in_array( $url[0], array( '/', '#', '?' ) ) &&
    ! preg_match('/^[a-z0-9-]+?.php/i', $url) )
    $url = 'http://' . $url;