I'm pretty sure you don't have to die ON the Quest Bed or Crypt, as we see with Jade in Cascade. Also, say you die on the quest bed, is the body that died's soul left in the dream bubbles? In Terezi R3M3MB3R we see the John that died on the quest bed there, but Jade says that while she was dead she was in the dream bubbles but then woke up, so it seems they were merged?
I mean, Jade was brought to the Quest Bed really quickly after death. You don’t need to die immediately on it, but there IS a time limit for going God Tier- Usually, your Dream Self will start to die, so you have until it dies to put your corpse in the bed. Crypts are weirder though because they allow ascension without a secondary you, so I’m assuming it requires instant death on it? Otherwise it’d be way too easy to just bring everyone’s corpses to the moon.
And that’s where the Consciousness problem comes in! Consciousness as a stream of being, and Soul as snapshots in different points of that stream. When you go to sleep and wake up on Prospit or Derse, your consciousness continues as if you were the same being, but once either body or dream self die, there’s a split. One part dies for good, and the other continues to live on. Which are you? That’s a philosophical conundrum, and very similar to the whole Teleporter dilemma- If you’re not warping somewhere, rather, having your atomical structure undone, then reformed somewhere else, are you the original anymore? Jade is briefly in the Bubbles and learns some stuff, but the issue is- If the Soul snaps back to the body, then it’s the Soul of the Dream Self that gets left behind, either assimilated into one and sort of erased, or to wander the Bubbles, and if it doesn’t snap back and it remains there while the God Tier retains the memories of the other’s Soul, then the original body’s Soul is left to wander the Bubbles! There’s really no winning move, God Tier requires a sacrifice, one way or another, you’re risking absolute oblivion or losing a part of your ‘self’. Or perhaps ‘gaining’ a part of yourself? However you may want to see it.