This requires the Oasis Mod Loader! Install it here! https://github.com/ahk1221/oasis-sml/
Simply build the .dll file and copy it to your Subnautica/Subnautica_Data/SMods folder. Don't forget to copy the assetbundle files(.asset and .manifest) present in the AssetBundle folder too!
Crafting and ammo now both work! Yay! You will need Warp Scales (knife Warpers) to make a Warp Battery, which you can then use to craft the Warp Cannon.
warpcannon - Warp Cannon
warpscales - Warp Scale (resource obtained by knifing Warpers. used for crafting Warp Batteries.)
warpbattery - Warp Battery (used to power Warp Cannons)