In classes/item.phpline 135, you are testing the result of strpos($order_sql, ',') by using >=0. When strpos returns false, the test succeeds, and the first character of $order_sql is removed. The error occurs if, for example, you have sortcats="cat_order" in a shortcode. Replacing the line with the following, prevents various warnings being issued and also makes the sort work again:
if ($p !== false && $p >= 0)
In classes/item.phpline 135, you are testing the result of strpos($order_sql, ',') by using >=0. When strpos returns false, the test succeeds, and the first character of $order_sql is removed. The error occurs if, for example, you have sortcats="cat_order" in a shortcode. Replacing the line with the following, prevents various warnings being issued and also makes the sort work again: if ($p !== false && $p >= 0)