When I try to load the recipe via NEI/JEI via the plus button it does not show a crafting result. When I then pickup one of the glass slots and try to replace it, I get this crash: https://paste.ee/p/cVOlM

Using FluxNetworks 1.2.9
Forge 12.18.3.2511

edit: Seems you forgot that stacks can be null in 1.10.2, probably just need a null check there.