On lines 214-216 in plugins/finder/categories/categories.php $item variable is used, but it's never defined nor passed to the function. I just got a notice because of this when I was deleting categories. There is a comment written just above those lines

                /* TODO: The $item variable does not seem to be used at all
                $query = clone($this->getStateQuery());
                $query->where('a.id = ' . (int) $pk);

                // Get the published states.
                $this->db->setQuery($query);
                $item = $this->db->loadObject();
                */

But apparently it is used in some cases. I also have to add that I could not reproduce the problem again when I set a test in a new environment, so I have no idea under which conditions it's actually triggered, just that it exists for sure.