[2.0.72] Undo item has nil entries

[Natha]

Steps to reproduce:
1. Build a belt
2. Super-force build a splitter (belt is now marked for deconstruction and splitter ghost is created)
3. Place the belt again in another direction on the same position (splitter ghost is removed)
4. Print the last undo item. The first entry is nil

Code: Select all

/c game.print(serpent.line(game.player.undo_redo_stack.get_undo_item(1)))