Rewriting from scratch. Fixing old code is just less fun.

_rooms.js

@@ -0,0 +1,21 @@
+module.exports = {
+	start: function () {
+		for (const room_name in Game.rooms) {
+			const room = Game.rooms[room_name];
+			room.init();
+		}
+	},
+
+	update: function () {
+		for (const room_name in Game.rooms) {
+			const room = Game.rooms[room_name];
+			if (room.isNewLevel()) {
+				// Place new building types if the max construcion sites isn't achieved yet.
+				if (!room.isConstructionQueueFull()) {
+					room.planRoads();
+					room.planStructures();
+				}
+			}
+		}
+	}
+}