An amount refunded should be numeric, I was receiving pHP notices that a non numeric value was encountered. Seems this is something potentially new as of PHP 7.1? Is there any reason we should **not** return a float here? Any null or empty response from the SQL query would be 0, which would still be accurate for the total that was refunded for that order.
```2018/01/27 16:50:50 [error] 46797#0: *2930 FastCGI sent in stderr: "PHP message: PHP Warning: A non-numeric value encountered in /wp-content/plugins/woocommerce/includes/admin/meta-boxes/views/html-order-items.php on line 212
PHP message: PHP Stack trace:
PHP message: PHP 1. include() /cms/wp-admin/post.php:174
PHP message: PHP 2. do_meta_boxes() /cms/wp-admin/edit-form-advanced.php:714
PHP message: PHP 3. WC_Meta_Box_Order_Items::output() /cms/wp-admin/includes/template.php:1063
PHP message: PHP 4. include() /wp-content/plugins/woocommerce/includes/admin/meta-boxes/class-wc-meta-box-order-items.php:41```