Undo breaks in TileMap editor after a while and engine crashes after trying to close the tab

[ShatReal]

Godot version

3.4-beta5, 3.3.3

System information

Windows 10

Issue description

Error happens on both versions listed. After I place down tiles for a while, the undo stops working and shows the message "Nothing to undo". Closing the tab crashes the engine.

Steps to reproduce

Place down tiles in a TileMap until it happens.

Minimal reproduction project

No response

[Calinou]

See also https://github.com/godotengine/godot/issues/45559 and https://github.com/godotengine/godot/issues/15506.

[Torguen]

I think this is the famous error where something like "condition -> true" appears in the console. This is being a pain when working with the tilemap editor.