Run luacheck and fix the warnings.

.luacheckrc

+unused_args = false
+allow_defined_top = true
+
+read_globals = {
+	"minetest",
+	"vector", "ItemStack",
+	"default",
+	"stairs", "doors", "xpanes",
+}

chess.lua

@@ -504,9 +504,9 @@ function realchess.move(pos, from_list, from_index, to_list, to_index, _, player
 
 	meta:set_string("playerWhite", playerWhite)
 	meta:set_string("playerBlack", playerBlack)
-	meta:set_string("lastMove", thisMove)
+	lastMove = thisMove
+	meta:set_string("lastMove", lastMove)
 	meta:set_int("lastMoveTime", minetest.get_gametime())
-	local lastMove = meta:get_string("lastMove")
 
 	if lastMove == "black" then
 		minetest.chat_send_player(playerWhite, "["..os.date("%H:%M:%S").."] "..

enchanting.lua

@@ -127,7 +127,6 @@ function enchanting.destruct(pos)
 end
 
 function enchanting.timer(pos)
-	local node = minetest.get_node(pos)
 	local num = #minetest.get_objects_inside_radius(pos, 0.9)
 
 	if num == 0 then

nodes.lua

@@ -354,7 +354,6 @@ xdecor.register("painting_1", {
 	inventory_image = "xdecor_painting_empty.png",
 	wield_image = "xdecor_painting_empty.png",
 	paramtype2 = "wallmounted",
-	wield_image = "xdecor_painting_empty.png",
 	sunlight_propagates = true,
 	groups = {choppy=3, oddly_breakable_by_hand=2, flammable=2, attached_node=1},
 	sounds = default.node_sound_wood_defaults(),

rope.lua

@@ -9,9 +9,7 @@ end)
 
 function rope.place(itemstack, placer, pointed_thing)
 	if pointed_thing.type == "node" then
-		local under = pointed_thing.under
-		local above = pointed_thing.above
-		local pos = above
+		local pos = pointed_thing.above
 		local oldnode = minetest.get_node(pos)
 		local stackname = itemstack:get_name()
 		if minetest.is_protected(pos, placer:get_player_name()) then return end

workbench.lua

@@ -229,7 +229,8 @@ for i = 1, #nodes do
 	local def = minetest.registered_nodes[node]
 
 	if d[3] then
-		local groups, tiles = {}, {}
+		local groups = {}
+		local tiles
 		groups.not_in_creative_inventory = 1
 
 		for k, v in pairs(def.groups) do