Notice: Undefined variable: singleurl and a proposed solution

Having enabled the debug feature of WordPress I received the following message about the plugin
“Notice: Undefined variable: singleurl in \wp-content\plugins\fd-footnotes\fdfootnotes.php on line 130”
despite the fact that the plugin was working properly.

I declared the singleurl variable on fdfootnotes.php line 115 $singleurl=” and resolved the issue
Hope is the correct way to declare the variable and be included in the next update.
Thanks for the plugin

https://www.ads-software.com/plugins/fd-footnotes/