Undefined property

I’m currently building a new site and as I was publishing a new page, I got the following error at the top.

Notice: Undefined property: Post_Hit_Counter::$script_suffix

this is in wp-content/plugins/post-hit-counter/includes/class-post-hit-counter.php on line 507

I thought you might like to know.

https://www.ads-software.com/plugins/post-hit-counter/