Fix radiation protection when armor group is not set (#509)

coil

2019-12-30 da95be53ec5703e808233d7b45fc42fb500863dd

 technic/tools/sonic_screwdriver.lua

@@ -86,7 +86,7 @@
      return itemstack
   end,
})
 

minetest.register_craft({
   output = "technic:sonic_screwdriver",
   recipe = {