I really need to utilize this "Fix InventoryDef.Properties causing NullReferenceException" - how do I do it? (New to everything regarding github)

[KalleGH]

As the title states. I'm a complete beginner in game development, c# and github :P
So just finding this took me ages. I get a null issue when using InventoryDef.properties which I just cant get around. And my entire game revolves around fetching these properties (tags basically..)

I saw this fix in the brashes but it's old AF and is missing like the latest 200 patches.
Fix InventoryDef.Properties causing NullReferenceException

HOW do I get to use this ONE line of edited code?
I'm using unity.

Please please please save the noob!