How to properly access action asset?

I’ve been following this:

And implemented the script as in docs. But when I do .Enable on the asset, it simply throws a null ref exception.

Is the asset automatically injected, or it has to be found / instantiated manully?
Docs are confusing.

Edit: Okay it seems like you should just do = new yourassetmapping();

OH MY GOD Thank you so much for figuring this out!