KML file/layer doesn't added

[MandanaMoshref]

I prefer this repository as it provides the possibility to differ the base map from the spatial widget (ckanext-spatial).

I test the latest branch "Master" and it doesn't add any kml layer. However, it works for wms.
So, I assume the implementation is fine but just doesn't work with kml. I tested different kml files, still no success.

Is this a bug or am I doing something wrong?

inside the basemaps.json I have OpenStreepMap and mapbox (but only it reads the first one which is OSM).

I am using ckan 2.8.0 on my local machine.