So basically Wreden personified an aspect of his psyche as a game developer and called him Coda, through which he explores different themes. It's easy to realize that Coda's none other than Wreden himself when he says early on that Coda stopped making games in 2011. Yep, the same year The Stanley Parable came out.
I understand that it is a rather personal story, shedding light on some of the developer's struggles in life. Starting with examining and attempting to understand what he was going through in the initial stages to finally realizing that he was the one holding himself back. The Beginner's Guide perhaps is Wreden summarizing his pondering over said struggles and realizations into something tangible, in order for him to solidify his notion of moving on by having some sort of reference for the future. The laser glitch is a major indicator of this and here's why:
You encounter the laser glitch a total of 2 times. The first encounter is very early in the game, and what happens is you start to levitate over the structure of a relatively small labyrinth, Wreden explains how this event was a turning point for "Coda", triggering him to move on. The 2nd and last time you encounter it is at the very end of the game, this time overlooking a labyrinth an order of magnitude bigger than the previous one.
What I think based on the information we were given is that the labyrinths seem to symbolize struggle. The size difference seems to indicate the accumulation and culmination of Wreden's inner struggles over time, and floating away from the larger labyrinth during the game's ending is Wreden himself finally finding the exit and moving on.
And looking down at that thing...
http://i.imgur.com/C70akEN.png
It looks pretty daunting doesn't it? Who would want to go back there.