Unhandled Error!

Trying to get property of non-object

Document	product_partial
Document type	CMS partial
Line	4
Exception class	Cms_ExecutionException

Code Highlight

<?= open_form() ?>
    <?= flash_message() ?>
    <input type="hidden" name="redirect" value="<?= site_url('cart') ?>" />
    <? $this->render_partial('shop:image_slider', array('images'=>$product->images)) ?>
    <div id="store-product-description">
        <? if ($product->is_out_of_stock()): ?>
        <img src="<?= root_url('/resources/images/outofstock.png') ?>" class="outofstock" />
        <? endif; ?>
        <h2><strong><?= $product->name ?></strong><br />
        <?
            $is_discounted = $product->is_discounted();
        ?>
        <strong>

#	Document	Type
2	product_partial	CMS partial
1	Product details page.	CMS page