By walking around, the walls will start to degrade and disappear; once they do, you can walk out and the game ends.
Oh! I was wondering why specifically checking the empty vending machine repeatedly made the walls disappear, I hadn't realized just walking did it too.
(Anyway this is nice! I like the dialogue counter, replaying to discover steps I might have skipped. Also I have to salute the effort to make a hack just for this haha)