Issue with Numnia and multiple backpacks

Running Numina/Modular Powersuits and Sophisticated Backpacks on my server and playing around when I get the following crash and report: https://gist.github.com/CloWnicide/b6229e5623d8b218df4f25e829791254

Currently running - Forge: 36.1.16, Numina: 1.16.4-2.0.10, Sophisticated Backpacks: 1.16.4-2.4.0.259