Wikimedia Bugzilla is closed!

On displaying a category page that contains sub-categories, my site (running on svn trunk) shows the following fatal PHP error:

Notice: Undefined variable: title in ./includes/CategoryPage.php on line 172

Fatal error: Call to a member function getPrefixedText() on a non-object in ./includes/CategoryPage.php on line 193

On examining the relevant function, the error seems immediately apparent:

  /**
   * Add a subcategory to the internal lists, using a Category object
   */
  function addSubcategoryObject( Category $cat, $sortkey, $pageLength ) {
    // Subcategory; strip the 'Category' namespace from the link text.
    $this->children[] = $this->getSkin()->link(
      $cat->getTitle(),
      null,
      array(),
      array(),
      array( 'known', 'noclasses' )
    );

    $this->children_start_char[] = $this->getSubcategorySortChar( $title, $sortkey );
  }

In the last line, the variable $title is used, when it hasn't been defined or passed as an argument. This should probably be replaced by $cat->getTitle(), as earlier in the function.

Making that replacement fixed the error for me.