error after editing & re-saving page with the shortcode

Hi. I’m having some issue with PHP.

Fatal error: Call to a member function list_attributes() on a non-object in /home/wpmash/public_html/incadventures/wp-content/plugins/shortcodes-ui/shortcode-maker.php(1197) : eval()’d code on line 4

I only get the error when I save or resave a post that has the associated shortcode. And what’s really odd is I only get the error sometimes when saving, not every time.

[attribs]

I’m adding the following php into php section as advanced mode:

global $woocommerce, $post, $product;
echo "<div class='fast-facts'>";
echo "<h2>Fast Facts</h2>";
$product->list_attributes();
echo "</div>";

This code for displaying WooCommerce custom attributes within a page seems to work sometimes, but as I said, throws error after editing and re-saving the page with the shortcode in it.

I’ve tried changing the setting: ‘my code uses PHP echo’ to ‘return’, but it seems to work the same either way (I would think ‘echo’ would apply here).

I get the php error on a white screen. If I reopen the page editor on another browser tab the page changes actually saved properly, and the page displays the WooCommerce attributes on the page as expected.

http://ww.wp.xz.cn/extend/plugins/shortcodes-ui/