It needed an update - there's it.

shop.lua

@@ -87,7 +87,9 @@ local function get_exchange_shop_tube_config(mode)
 end
 
 minetest.register_on_player_receive_fields(function(sender, formname, fields)
-	if (formname == "bitchange:shop_formspec") then
+	if (formname ~= "bitchange:shop_formspec") then
+		return
+	end
 	local player_name = sender:get_player_name()
 	local pos = exchange_shop[player_name]
 	local meta = minetest.get_meta(pos)
@@ -154,6 +156,30 @@ minetest.register_on_player_receive_fields(function(sender, formname, fields)
 				err_msg = "The 'Owner gives' field can not contain multiple times the same items, contact the shop owner."
 			end
 		end
+		if(err_msg == "") then --?shop has space
+			local shop_has_space = true
+			for i, item in pairs(cust_ow) do
+				if (not shop_inv:room_for_item("custm",item)) then
+					shop_has_space = false
+					break
+				end
+			end
+			if(not shop_has_space) then
+				err_msg = "The stock in the shop is full."
+			end
+		end
+		if(err_msg == "") then --?shop has items
+			local shop_has_items = true
+			for i, item in pairs(cust_og) do
+				if (not shop_inv:contains_item("stock",item)) then
+					shop_has_items = false
+					break
+				end
+			end
+			if(not shop_has_items) then
+				err_msg = "The shop is empty and can not give you anything."
+			end
+		end
 		if(err_msg == "") then --?player has space
 			local player_has_space = true
 			for i, item in pairs(cust_og) do
@@ -178,30 +204,6 @@ minetest.register_on_player_receive_fields(function(sender, formname, fields)
 				err_msg = "You do not have the needed items."
 			end
 		end
-			if(err_msg == "") then --?shop has space
-				local shop_has_space = true
-				for i, item in pairs(cust_ow) do
-					if (not shop_inv:room_for_item("custm",item)) then
-						shop_has_space = false
-						break
-					end
-				end
-				if(not shop_has_space) then
-					err_msg = "Exchange shop: The stock in the shop is full."
-				end
-			end
-			if(err_msg == "") then --?shop has items
-				local shop_has_items = true
-				for i, item in pairs(cust_og) do
-					if (not shop_inv:contains_item("stock",item)) then
-						shop_has_items = false
-						break
-					end
-				end
-				if(not shop_has_items) then
-					err_msg = "The shop is empty and can not give you anything."
-				end
-			end
 		if(err_msg == "") then --?exchange
 			local fully_exchanged = true
 			for i, item in pairs(cust_ow) do
@@ -234,7 +236,6 @@ minetest.register_on_player_receive_fields(function(sender, formname, fields)
 	elseif(fields.vcustm and bitchange_has_access(shop_owner, player_name) and not fields.quit) then
 		minetest.show_formspec(sender:get_player_name(),"bitchange:shop_formspec",get_exchange_shop_formspec(2, pos, title))
 	end
-	end
 end)
 
 minetest.register_node("bitchange:shop", {
@@ -268,7 +269,9 @@ minetest.register_node("bitchange:shop", {
 	can_dig = function(pos,player)
 		local meta = minetest.get_meta(pos);
 		local inv = meta:get_inventory()
-		if(inv:is_empty("stock") and inv:is_empty("custm") and inv:is_empty("custm_ej") and inv:is_empty("cust_ow") and inv:is_empty("cust_og") and inv:is_empty("cust_ej")) then
+		if(inv:is_empty("stock") and inv:is_empty("custm") and 
+			inv:is_empty("custm_ej") and inv:is_empty("cust_ow") and 
+			inv:is_empty("cust_og") and inv:is_empty("cust_ej")) then
 			return true
 		else
 			minetest.chat_send_player(player:get_player_name(), "Can not dig exchange shop, one or multiple stocks are in use.")
@@ -289,16 +292,23 @@ minetest.register_node("bitchange:shop", {
 		else
 			view = 1
 		end
-		minetest.show_formspec(player_name,"bitchange:shop_formspec",get_exchange_shop_formspec(view, pos, meta:get_string("title")))
+		minetest.show_formspec(player_name, "bitchange:shop_formspec", get_exchange_shop_formspec(view, pos, meta:get_string("title")))
 	end,
 	allow_metadata_inventory_move = function(pos, from_list, from_index, to_list, to_index, count, player)
 		local meta = minetest.get_meta(pos)
-		if (not bitchange_has_access(meta:get_string("owner"), player:get_player_name())) then
+		if bitchange_has_access(meta:get_string("owner"), player:get_player_name()) then
-			return 0
-		end
 			return count
+		end
+		return 0
 	end,
     allow_metadata_inventory_put = function(pos, listname, index, stack, player)
+		if player:get_player_name() == ":pipeworks" then
+			return stack:get_count()
+		end
+		if listname == "custm" then
+			minetest.chat_send_player(player:get_player_name(), "Exchange shop: Please press 'Customers stock' and insert your items there.")
+			return 0
+		end
 		local meta = minetest.get_meta(pos)
 		if (bitchange_has_access(meta:get_string("owner"), player:get_player_name()) and (listname ~= "cust_ej") and (listname ~= "custm_ej")) then
 			return stack:get_count()
@@ -306,6 +316,9 @@ minetest.register_node("bitchange:shop", {
 		return 0
 	end,
     allow_metadata_inventory_take = function(pos, listname, index, stack, player)
+		if player:get_player_name() == ":pipeworks" then
+			return stack:get_count()
+		end
 		local meta = minetest.get_meta(pos)
 		if (bitchange_has_access(meta:get_string("owner"), player:get_player_name()) or (listname == "cust_ej")) then
 			return stack:get_count()