Chewbacca probably spends more time on ships nowadays than he does on planets, and he's never learned to like it, but at least the Millennium Falcon is familiar -- he knows what doorways to duck and where Han hides the good snacks.

On the Death Star though he can't help but feel completely and utterly exposed -- even if no one gives them a second glance and the hallways stretch up and out forever, the whole place just feels dead, like he could turn a corner and never see a sentient being again.

If he dies here, he'll be unceremoniously dumped into space, and he'll never feel solid ground beneath his feet again; perhaps his spirit will wander these halls forever -- so is it any wonder that the thought makes him shiver?