self destruct book entity when table gone

mods/ITEMS/mcl_enchanting/init.lua

@@ -149,19 +149,22 @@ minetest.register_craftitem("mcl_enchanting:book_enchanted", {
 minetest.register_alias("mcl_books:book_enchanted", "mcl_enchanting:book_enchanted")
 
 local spawn_book_entity = function(pos, respawn)
-	if respawn then
-		-- Check if we already have a book
-		local objs = minetest.get_objects_inside_radius(pos, 1)
-		for o=1, #objs do
-			local obj = objs[o]
-			local lua = obj:get_luaentity()
-			if lua and lua.name == "mcl_enchanting:book" then
-				if lua._table_pos and vector.equals(pos, lua._table_pos) then
-					return
-				end
+	local cnt=0
+	-- Check if we already have books within 5 nodes distance to avoid too many entities
+	local objs = minetest.get_objects_inside_radius(pos, 5)
+	for o=1, #objs do
+		local obj = objs[o]
+		local lua = obj:get_luaentity()
+		if lua and lua.name == "mcl_enchanting:book" then
+			if respawn and lua._table_pos and vector.equals(pos, lua._table_pos) then
+				return
 			end
+			cnt=cnt+1
 		end
 	end
+	
+	if cnt > 10 then return end
+
 	local obj = minetest.add_entity(vector.add(pos, mcl_enchanting.book_offset), "mcl_enchanting:book")
 	if obj then
 		local lua = obj:get_luaentity()
@@ -192,8 +195,8 @@ minetest.register_entity("mcl_enchanting:book", {
 		local old_player_near = self._player_near
 		local player_near = false
 		local player
-		for _, obj in ipairs(minetest.get_objects_inside_radius(vector.subtract(self.object:get_pos(), mcl_enchanting.book_offset), 2.5)) do
-			if obj:is_player() then
+		for _,obj in pairs(minetest.get_connected_players()) do
+			if vector.distance(obj:get_pos(),self.object:get_pos()) < 2.5 then
 				player_near = true
 				player = obj
 			end
@@ -210,6 +213,13 @@ minetest.register_entity("mcl_enchanting:book", {
 		end
 		self._player_near = player_near
 		mcl_enchanting.check_animation_schedule(self, dtime)
+		
+		if self._table_pos then
+			local tn=minetest.get_node_or_nil(self._table_pos)
+			if tn and tn.name ~= "mcl_enchanting:table" then
+				self.object:remove()
+			end
+		end
 	end,
 })
 
@@ -309,8 +319,8 @@ minetest.register_abm({
 	nodenames = "mcl_enchanting:table",
 	action = function(pos)
 		local playernames = {}
-		for _, obj in ipairs(minetest.get_objects_inside_radius(pos, 15)) do
-			if obj:is_player() then
+		for _,obj in pairs(minetest.get_connected_players()) do
+			if vector.distance(obj:get_pos(),pos) < 15 then
 				table.insert(playernames, obj:get_player_name())
 			end
 		end