Coding error

In the current release (1.6.21), if run on PHP 7.2, you get this log message thousands of times in 48h:

PHP Warning: Use of undefined constant aux – assumed ‘aux’ (this will throw an Error in a future version of PHP) in /home/webdig/public_html/blog.webdig.pt/wp-content/plugins/nelio-content/includes/class-nelio-content-auto-sharer.php on line 214