find/fix simple error in code

I am a starting programmer and made a very simple plugin that causes a fatal error when i install it on my live site. (on my testing site offline it does work correctly). I identified a small piece of code that is the cause. I need someone to tell me what is wrong with the code and how I can solve it. Please see the code below: // Hook in add_filter( 'woocommerce_checkout_fields' , 'ggs_custom_override_checkout_fields' ); // Our hooked in function - $fields is passed via the filter! function ggs_custom_override_checkout_fields( $fields ) { if ( hotel_category_in_cart() ){ $fields['billing']['billing_company'] = array( 'label' => __('Room Number', 'woocommerce'), 'placeholder' => _x('', 'placeholder', 'woocommerce'), 'required' => false, 'class' => array('form-row-wide'), 'clear' => true ); unset($fields['billing']['billing_country']); unset($fields['billing']['billing_first_name']); unset($fields['billing']['billing_last_name']); echo '<link href="css/[login to view URL]" rel="stylesheet" type="text/css" />'; } return $fields; } /** * Check if a HOTEL product category is in the cart */ function hotel_category_in_cart() { // Add your special category slugs here $categories = array( 'hotel' ); // Products currently in the cart $cart_ids = array(); // Categories currently in the cart $cart_categories = array(); // Find each product in the cart and add it to the $cart_ids array foreach( WC()->cart->get_cart() as $cart_item_key => $values ) { $cart_product = $values['data']; $cart_ids[] = $cart_product->id; } // Connect the products in the cart w/ their categories foreach( $cart_ids as $id ) { $products_categories = get_the_terms( $id, 'product_cat' ); // Loop through each product category and add it to our $cart_categories array foreach ( $products_categories as $products_category ) { $cart_categories[] = $products_category->slug; } } // If one of the special categories are in the cart, return true. if ( ! empty( array_intersect( $categories, $cart_categories ) ) ) { return true; } else { return false; } }