Does up to the bossfight. The boss level is done before the cat maze level because otherwise it messes up the position that is used for the warp to skip the first phase of the bossfight.
Also found out that the blue laser actually does less damage to the boss than the red laser, I think that's the case anyway, so I got to redo something somewhere to collect a red laser, unless the glitch thing can be used to somehow spawn red laser shots, which I wouldn't be surprised if it was a thing tbh.
Edit: Ended up collecting the red laser at the start of the third level, pretty fast one to pick up, about 2 seconds, and the teleport gets you to the same spot anyway so the rest of the level is about the same.