Shipping Options plugin

th_shipping_options.php

<?php
/*
Plugin Name: TH Shipping Options
Plugin URI: NA
Description: TH Shipping Options plugin
Version: 1.0.0
Author: Vj
Author URI: www.wooforce.com
*/

define("PV_ATTRIBUTE", "vendor");
if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly

/**
 * Check if WooCommerce is active
 */
if ( in_array( 'woocommerce/woocommerce.php', apply_filters( 'active_plugins', get_option( 'active_plugins' ) ) ) ) {
	if ( ! class_exists( 'TH_Shipping_Options' ) ) {
		class TH_Shipping_Options {
			/**
			 * Constructor for your shipping class
			 *
			 * @access public
			 * @return void
			 */
			public function __construct() {
				// take care of anything else that needs to be done immediately upon plugin instantiation, here in the constructor.
				add_filter( 'woocommerce_cart_shipping_packages', array( &$this, 'th_woocommerce_cart_shipping_packages') );
				// Overriding template to introduce vendor names along with standard labels across shipping packages.
				//add_filter( 'woocommerce_locate_template', array( $this, 'th_woocommerce_locate_template' ), 10, 3 );
			}
			
			function th_woocommerce_locate_template( $template, $template_name, $template_path ) { 
				if('cart/cart-shipping.php' == $template_name)
				{
						$path = plugin_dir_path( __FILE__ ) . '/woocommerce/templates/' . $template_name;  
						return file_exists( $path ) ? $path : $template;
				}
				return $template;
			}
	
			function th_woocommerce_cart_shipping_packages( $packages ) {
				// Reset the packages
				$packages = array();
				$vendor_items_map = array();

				foreach ( WC()->cart->get_cart() as $item ) {
					$product_id = $item['product_id'];
					$vendors = get_product_vendors( $product_id  );
					if ( $item['data']->needs_shipping() ) {
						if($vendors) {
							foreach( $vendors as $vendor ) {
								// Expecting/assuming there is only one Vendor assigned per product. Hm.
								$vendor_items_map[$vendor->ID][] = $item;
								break;
							}
						}
						// No product vendor associated with item.
						else {
							$vendor_items_map['0'][] = $item;
						}
					}
				}
				
				foreach($vendor_items_map as $key => $vendor_items) {
					$packages[] = array(
						//'ship_via' => array( 'flat_rate' ),
						'contents' => $vendor_items,
						'contents_cost' => array_sum( wp_list_pluck( $vendor_items, 'line_total' ) ),
						'applied_coupons' => WC()->cart->applied_coupons,
						'destination' => array(
							'country' => WC()->customer->get_shipping_country(),
							'state' => WC()->customer->get_shipping_state(),
							'postcode' => WC()->customer->get_shipping_postcode(),
							'city' => WC()->customer->get_shipping_city(),
							'address' => WC()->customer->get_shipping_address(),
							'address_2' => WC()->customer->get_shipping_address_2()
						)
					);	
				}
				
				return $packages;
			}
		}
		
		// finally instantiate our plugin class and add it to the set of globals
		$GLOBALS['th_shipping_options_init'] = new TH_Shipping_Options();
	}

	// Start up this plugin
	add_action( 'init', 'TH_Shipping_Options' );
	function TH_Shipping_Options() {
		global $TH_Shipping_Options;
		$TH_Shipping_Options = new TH_Shipping_Options();
	}
}

I'm having an issue with this plugin causing the cart and checkout page to not load any of the woocommerce content. It displays a blank page for both.