The official speedrunnning rules from speedrun.com for Portal 2 say:
Timing starts when you gain control of Chell (crosshair appearing) and ends on when the moon is hit (regardless of whether you die in the credits)
I haven't been able to find out what that parenthetical of "regardless of whether you die in the credits" means. Searching online gives me obviously-fake alternate endings, with nothing that looks like it's in the real game (some have claims that they were endings considered in development, but even if I believe that they don't seem to be in the released version).
What is that sentence referring to, and how do you trigger it? Is it possible to have Chell die at the end of Portal 2?