Except if you blow a CD, have stone-skin and an aldo on you, the only reason you are going to die from Vishap's jump due to a missed DK is if you are under-geared for the encounter. Squishier casters would most likely die or be close to death depending on their HP values, but the jump itself isn't a mechanic designed to one shot you.
It doesn't really matter whether it was "designed to" or not. The fact remains that it does.

And I'm not undergeared for the fight, but nice try.