Plugin break Walker Menu

I have just downloaded/installed/activated the plugin and it breaks the Walker_Nav_Menu. I get the following message: Notice: Undefined property: stdClass::$current in …/wp-content/themes/ebmt/functions.php on line 33. Line 33 is part of the following (I have made the line bold):

class top_bar_walker extends Walker_Nav_Menu {

function display_element( $element, &$children_elements, $max_depth, $depth=0, $args, &$output ) {
$element->has_children = !empty( $children_elements[$element->ID] );
$element->classes[] = ( $element->current || $element->current_item_ancestor ) ? ‘active’ : ”;
$element->classes[] = ( $element->has_children ) ? ‘has-dropdown not-click’ : ”;

parent::display_element( $element, $children_elements, $max_depth, $depth, $args, $output );
}

function start_el( &$output, $object, $depth = 0, $args = array(), $current_object_id = 0 ) {
$item_html = ”;
parent::start_el( $item_html, $object, $depth, $args );

$output .= ( $depth == 0 ) ? ‘<li class=”divider”>‘ : ”;

$classes = empty( $object->classes ) ? array() : (array) $object->classes;
if ( in_array(‘label’, $classes) ) {
$output .= ‘<li class=”divider”>‘;
$item_html = preg_replace( ‘/<a[^>]*>(.*)<\/a>/iU’, ‘<label>$1</label>’, $item_html );
}

if ( in_array(‘divider’, $classes) ) {
$item_html = preg_replace( ‘/<a[^>]*>( .* )<\/a>/iU’, ”, $item_html );
}

$output .= $item_html;
}

function start_lvl( &$output, $depth = 0, $args = array() ) {
$output .= “\n<ul class=\”sub-menu dropdown\”>\n”;
}

}

Any ides on how to get around this?