Attempting to undo while in end of turn decisions causes unresponsive game

[roed]

Playing against a bot, I had played seven schemes (two of which were overlords copying schemes), bought three banks, a bazaar and then an overlord.  I payed off two of the debt from the overlord, which brought me to the interface to select which cards should be placed on top of the deck from the schemes.  At that point I tried to undo.  The game became unresponsive, and I was eventually booted from the server.  Upon logging in again, the game resumed at a point 6 or 7 turns earlier, and the UI was completely unresponsive.  Reloading the page resumed into the same state.

In case this is related to server issues, the game occurred around 5:40am UTC.  There was a +Buy token on the Overlord pile and a +Card token on the Teacher pile.  Here's the full set:
Colonies/Plantina, Forge, Expand, Bank, Bazaar, Scavenger, Remake, Scheme, Castles, Peasant, Overlord, Salt the Earth, Lost Arts, Aqueduct.