Reminder to myself to fix this.

Stacktrace: https://gist.github.com/GirafiStudios/11c8fb2758cbd9fa6e3f76388c393fa1

Need to change this to value and do instanceof ItemStack check here

See https://github.com/mezz/JustEnoughItems/blob/1.10/src/main/java/mezz/jei/gui/Focus.java