Sorry! Update 1.2 broke the deeper part of the pit: it had no walls and no loot, so you could dig right out of the level. This hotfix fixes it.
Fixes
The walls and loot in the deeper part of the pit are back
If your save is outside the walls, you start again at the surface. You keep your money and upgrades
The bottom of the pit is now sealed, and the thin gaps where the wall sections meet are closed
Thanks for reporting it so quickly. If you still find a way out of the pit, tell us in the Steam discussions.
— Danny