That'd be something, people travel for 30 years to a distant planet, die four days later because something in the atmosphere we didn't account for and did not filter properly, or a crystalline fungus that eats away our suits.
Happens a lot in (bad) science fiction, and parody thereof.
People land on a planet, go "I wonder if the atmosphere is breathable?", then open their helmet and take a deep breath.
But I think by the time anyone is arriving on a planet around another star, it will be with biotechnology that allows adaptation to a rather wide variety of environments.
