LGTM.com - false positive: The value assigned to local variable is never used

**Description of the false positive**

The alert says "The value assigned to local variable 'resource_listed' is never used."

But the variable mentioned in that snippet IS used in the if-check several lines below.

At least, it is needed there for mypy type checking to be sure that the if-condition filters out all None values. Even if the logic hints that the None value is impossible due to the nearby condition on another variable.

**URL to the alert on the project page on LGTM.com**

https://lgtm.com/projects/g/nolar/kopf/snapshot/5f46eb0de621ecefaea2e5c3ca8965e1c213fea1/files/kopf/reactor/queueing.py?sort=name&dir=ASC&mode=heatmap#x20bb90834df18050:1