Hi 1omegazip,
You can go to the Backend > Extension > Templates > Templates > Ja_property and open the /html/mod_articles_category/owl.php file, then find line 229.
Replace this code:
<?php if(!empty($customs['price'])) :?>
With following code:
<?php if(isset($customs['price']->value) && !empty($customs['price']->value) ):?>
Hope this help!