bootstrap debug error

My localhost website using Sensitive theme has begun displaying white pages with content. I edited wp-config.php to activate the debug code (true) and received the following error when reloading my website:

Strict Standards: Declaration of sensitive_bootstrap_walker_nav_menu::start_lvl() should be compatible with Walker_Nav_Menu::start_lvl(&$output, $depth = 0, $args = Array) in C:\Users\Jacquelyn Harris\Documents\My Web Sites\wordpress\wp-content\themes\sensitive\libs\nav-menu-walker.class.php on line 117

Below you will find Lines 109-117 of my nav.menu.walker.php file:

//end this element
    $cb_args = array_merge( array(&$output, $element, $depth), $args);
    call_user_func_array(array(&$this, 'end_el'), $cb_args);

    }

    }

I have tried many variations of code with the values provided in the error code, but to no avail. Please help!