gargabecollector class php is throwing errors on lines 86 88 91

In the debug log, we’re frequently having the following info:
```
PHP Notice: Undefined index: group in /www/htdocs/{…}/wp-content/plugins/wp-less/lib/Garbagecollector.class.php on line 86.
```
Partially 7 lines are thrown after each other in the same second referring to lines `86/88/91`.

Could you support here / provide a fix that this is not logged to the error log?

Thx in advance!