Error incomponents - filtering

Hi!

For fewdays I noticed error with filtering. After added new item in my component I have nothing in my itemst list (backend).
It seems to filter when I not choose any filter, or filter like "show nothing".

I try to find error and I think I found.

It is in models/mycomponent.php
I change:
        $filter_created_by = $this->state->get("filter.created_by");
        if ($filter_created_by != '') {
            $query->where("a.`created_by` = '".$db->escape($filter_created_by)."'");
        }

to

        $filter_created_by = $this->state->get("filter.created_by");
        if ($filter_created_by') {
            $query->where("a.`created_by` = '".$db->escape($filter_created_by)."'");
        }

In components I create few days ago that second way was made, but from yesterday the first way

I hope it help but if you find the better way, tell me, please