Fatal error

Hello, and thank you very much for your plugin;)
I just noticed a bug when using the filter to have a list of products. If you access the product page and after you try (from the browser) to return to the search results there is a fatal error: Fatal error: Uncaught Error: Object of class WP_Post could not be converted to string in / home / clients / 7cfdab244278f55c07d25246cd07907f / web / wp-content / plugins / woo-product-filter / modules / woofilters / mod.php: 139
Could you tell me how to fix this problem? Thank you