AttributeError: ‘NoneType’ object has no attribute ‘name’ when working with NifSkope and Blender

[MrStuntAction]

I'm trying to make a mod that adds the Lonesome Road Courier Duster on top of the Old World Blues Sneaking Suit. I've been following this guide:

https://youtu.be/_u3T3vHCt1c

And everything's worked so far up until I import the .nif consisting of the skeleton+sneaking suit+duster:

https://imgur.com/a/Fk9xL8F

...into Blender to fix the clipping at what'd be the equivalent of 23:20 in the video. I then get the error AttributeError: ‘NoneType’ object has no attribute ‘name’ on Blender's console. As you can tell I pretty much have no idea on what I'm doing, any suggestions?