// Fix fatal error

blockwishlist-extra.tpl

@@ -23,6 +23,7 @@
 *  International Registered Trademark & Property of PrestaShop SA
 *}
 
+{if isset($wishlists) && count($wishlists) > 1}
 <div class="buttons_bottom_block">
 	<div id="wishlist_button">
 		<select id="idWishlist">
@@ -35,3 +36,10 @@
 		</button>
 	</div>
 </div>
+{else}
+<p class="buttons_bottom_block no-print">
+	<a id="wishlist_button" href="#" onclick="WishlistCart('wishlist_block_list', 'add', '{$id_product|intval}', $('#idCombination').val(), document.getElementById('quantity_wanted').value); return false;" rel="nofollow"  title="{l s='Add to my wishlist' mod='blockwishlist'}">
+		{l s='Add to wishlist' mod='blockwishlist'}
+	</a>
+</p>
+{/if}

blockwishlist.php

@@ -238,7 +238,11 @@ public function hookProductActions($params)
 
 		$this->smarty->assign(array(
 			'id_product' => (int)(Tools::getValue('id_product')),
-			'wishlists' => WishList::getByIdCustomer($cookie->id_customer),
+		));
+
+		if (isset($cookie->id_customer))
+			$this->smarty->assign(array(
+				'wishlists' => WishList::getByIdCustomer($cookie->id_customer),
 			));
 
 		return ($this->display(__FILE__, 'blockwishlist-extra.tpl'));