Also, for note, your issue resides in:
at gnu.trove.set.hash.THashSet.add(THashSet.java:112)
at cofh.thermalexpansion.util.crafting.SmelterManager.addTERecipe(SmelterManager.java:317)
That’s a bug in thermalexpansion, nothing to do with cofhlib or anything this fix could fix, it would require a ‘new’ asm to fix that, but since it had never been reported before I’m thinking it might be something in that fork you are running that is broken somehow?