menus – bootstrap-navwalker will not load


Trying to implement wp-bootstrap-navwalker.php into my made from scratch template for wordpress.
The File for the class-wp-bootstrap-navwalker.php is located in the root directory of my theme.

functions.php

function register_navwalker()

{
require_once get_template_directory() . ‘./class-wp-bootstrap-navwalker.php’;
}
add_action( ‘after_setup_theme’, ‘register_navwalker’ );

cover.php
With the code below within the <nav> and </nav> tags

  <?php
    wp_nav_menu( array(
        'theme_location'    => 'top-menu',
        'depth'             => 2,
        'container'         => 'div',
        'container_class'   => 'collapse navbar-collapse',
        'container_id'      => 'bs-example-navbar-collapse-1',
        'menu_class'        => 'nav navbar-nav',
        'fallback_cb'       => 'WP_Bootstrap_Navwalker::fallback',
        'walker'            => new WP_Bootstrap_Navwalker(),
    ) );
    ?>

When I save changes and reload my website, I get get the wp-bootstrap-navwalker page from github.

any help is much appreciated.