Access none for reference node with inventory system

I have been following the tutorial for the inventory UMG system by Wes bunn and have repeatedly been having an accessed none reference issue show up.
i seem to have everything else working fine. i am working in a third person template…
I have attached a link to a video in my google drive of the project how it currently is with the issue that is displaying.
I am uncertain how to fix this and need urgent help
thanks a bunch
https://drive.google.com/open?id=13StDvZBL6UU5NVEBgp5_9Mh-Od932x8o