Devil's first trial

I found an oddly-coloured wall. I was able to run right through it. I found myself on a small area outside the maze, with no wall preventing going outside. I walked past the edge and, sure enough, fell forever.

Part of game design is anticipating how players may break your game (or what may happen if, like here, you broke it yourself), and allowing for it. A quick check to see if the player was -XX units below the bottom of the maze, and either killing them or teleporting them back to the start, would work for this.