LGTM.com - false positive non-iterable type

**Description of the false positive**

`Non-iterable of class 'int' may be used in for-loop.` despite the lines above asserting that the variable is iterable; also the variable is never type hinted as `int`, I'm not sure where it is getting `int` from.

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

https://lgtm.com/projects/g/this-josh/felling/snapshot/13298590cd6d51b7a12fe217c4431d6f5d8dc035/files/felling/src/configure_felling.py?sort=name&dir=ASC&mode=heatmap#x5bfe95a28e9ebef2:1