Nil index check

- Solves #170

mods/throwing/functions.lua

@@ -33,9 +33,11 @@ function throwing_shoot_arrow (itemstack, player, stiffness, is_cross)
 	else
 		minetest.sound_play("throwing_bow_sound", {pos=playerpos})
 	end
-	obj:get_luaentity().player = player
-	obj:get_luaentity().inventory = player:get_inventory()
-	obj:get_luaentity().stack = player:get_inventory():get_stack("main", player:get_wield_index()-1)
+	if obj:get_luaentity() then
+		obj:get_luaentity().player = player
+		obj:get_luaentity().inventory = player:get_inventory()
+		obj:get_luaentity().stack = player:get_inventory():get_stack("main", player:get_wield_index()-1)
+	end
 	return true
 end