After Han, Chewbacca, Leia, and Luke get out of the trash compactor and are trying to find their way to the Millenium Falcon, they run into a couple of stormtroopers. One of them says, "It's them! Blast them!". Then Han shoots one of them and runs after the other. When Han runs by the stormtrooper he shot, the stormtrooper moves his leg out of the way so Han won't trip.
So, basically, what you're saying is that a laser blast can only kill, not wound? Because, you know, a wounded person tends to move around a bit, and not want to get stepped on as well. Essentially, I'm saying to not sweat this, as it's not really a slipup.
I don't think that Stormtrooper was really killed, I think he was only stunned, but I think it really is a slip up, because the Stormtrooper is not supposed to help Han (or Chewbacca, whoever) get past.