I'm getting a repeatable crash when equipping gas masks in the base game (DLC turned off). The checkpoint and docks were constructed fine, masks inserted, oxygen provided, but as soon as a dupe goes through the checkpoint, the game crashes.
1. Update to the 'Merge update'
2. Start a new game with DLC turned off
3. Make some oxygen masks, a checkpoint, and docks. Supply oxygen.
4. Have dupe go through the checkpoint to perform work.
I've attached a savegame that can reliably reproduce the crash for me. All i need to do is queue up a task down the shaft past the checkpoint. Log attached.
The only mod I have installed right now is a 'maximum zoom' mod. Seems unlikely to be the cause of the crash.
Edit: Created a new game with sandbox mode, added a checkpoint/mask/dock and got it some oxygen, and it crashed as soon as a dupe put it on.