Ex Nihilo Omnia version 1.2.2
Tinkers Construct 1.10.2-2.6.1
Mantle 1.10.2-1.1.3

Crash Log: https://gist.github.com/mallrat208/e0cce65c8ff89129d88295148a116178
Pretty Pictures: http://puu.sh/sTmjR/5818f5c896.png

Specifically in
ModCrooked which is being called during the HarvestDropsEvent and then generates the event again by the call on Line 59
block.getBlock().dropBlockAsItem(world, pos, world.getBlockState(pos), EnchantmentHelper.getEnchantmentLevel(Enchantments.FORTUNE, item));