Fix crash when doors.registered_doors isn't available

* Support doors and trapdoors from mods

Removed hardcoded door names and instead now use the API of the door mod to meseconify all doors and trapdoors that have been registered after the mods are finished loading.

* indentation as described by sfan5

mesecons_doors/init.lua

@@ -22,6 +22,11 @@ end
 local function meseconify_door(name)
 	if minetest.registered_items[name .. "_b_1"] then
 		-- old style double-node doors
+		if minetest.registered_items[name .. "_b_1"].mesecons then
+			minetest.log("info", "[mesecons_doors] Not touching door " .. name)
+			return
+		end
+
 		local function toggle_state1 (pos)
 			on_rightclick(pos, 1, name.."_t_1", name.."_b_2", name.."_t_2", {1,2,3,0})
 		end
@@ -47,6 +52,10 @@ local function meseconify_door(name)
 		})
 	elseif minetest.registered_items[name .. "_a"] then
 		-- new style mesh node based doors
+		if minetest.registered_items[name .. "_a"].mesecons then
+			minetest.log("info", "[mesecons_doors] Not touching door " .. name)
+			return
+		end
 		local override = {
 			mesecons = {effector = {
 				action_on = function(pos)
@@ -73,15 +82,6 @@ local function meseconify_door(name)
 	end
 end
 
-local doors_list = {
-	"doors:door_wood",
-	"doors:door_steel",
-	"doors:door_glass",
-	"doors:door_obsidian_glass",
-	"xpanes:door_steel_bar",
-}
-for i=1,#doors_list do meseconify_door(doors_list[i]) end
-
 -- Trapdoor
 local function trapdoor_switch(name)
 	return function(pos, node)
@@ -131,9 +131,17 @@ local function meseconify_trapdoor(name)
 	end
 end
 
-local trapdoors_list = {
-	"doors:trapdoor",
-	"doors:trapdoor_steel",
-	"xpanes:trapdoor_steel_bar"
-}
-for i=1,#trapdoors_list do meseconify_trapdoor(trapdoors_list[i]) end
+minetest.register_on_mods_loaded(function()
+	if doors.registered_doors ~= nil then -- registered_doors is not always available
+		for k,_ in pairs(doors.registered_doors) do
+			if k:find("_a$") then
+				meseconify_door(k:sub(1,-3))
+			end
+		end
+		for k,_ in pairs(doors.registered_trapdoors) do
+			if not k:find("_open$") then
+				meseconify_trapdoor(k)
+			end
+		end
+	end
+end)