Replace deprecated get_metadata() calls (luanti-org#3142)

Author: Niklp09

mods/default/chests.lua

@@ -163,12 +163,12 @@ function default.chest.register_chest(prefixed_name, d)
 			local itemstack = player:get_wielded_item()
 			local key_meta = itemstack:get_meta()
 
-			if itemstack:get_metadata() == "" then
+			if itemstack:get_meta():get_string("") == "" then
 				return
 			end
 
 			if key_meta:get_string("secret") == "" then
-				key_meta:set_string("secret", minetest.parse_json(itemstack:get_metadata()).secret)
+				key_meta:set_string("secret", minetest.parse_json(itemstack:get_meta():get_string("")).secret)
 				itemstack:set_metadata("")
 			end
 

mods/default/craftitems.lua

@@ -57,7 +57,7 @@ local function book_on_use(itemstack, user)
 	local page, page_max, lines, string = 1, 1, {}, ""
 
 	-- Backwards compatibility
-	local old_data = minetest.deserialize(itemstack:get_metadata())
+	local old_data = minetest.deserialize(itemstack:get_meta():get_string(""))
 	if old_data then
 		meta:from_table({ fields = old_data })
 	end

mods/default/functions.lua

@@ -803,7 +803,7 @@ function default.can_interact_with_node(player, pos)
 		local key_meta = item:get_meta()
 
 		if key_meta:get_string("secret") == "" then
-			local key_oldmeta = item:get_metadata()
+			local key_oldmeta = item:get_meta():get_string("")
 			if key_oldmeta == "" or not minetest.parse_json(key_oldmeta) then
 				return false
 			end