Cabin wreckage scene: why did Aaron Cross stop digging further?

He doesn't stop digging because he ran into something, he stops digging because he realizes it is a lost cause to look for the chems. As he is digging you see what's left of the chems in the snow, both blues and greens. You also notice there aren't any intact enough to salvage. Later in the movie when you see when he goes to take some chems, there are only fragments of one. I would assume this what is left of what he salvaged from the wrecked cabin. Other than the realization, there is nothing there which would make him stop digging.

This is an error in the movie. Since the blue and green snow are clearly melted chems, scooping up the blue snow in it's entirety would give him a liquid source of his meds. Better than nothing. He's too smart to not take that with him to sustain his needs until he can find more...

Definitely a plot hole in the movie or just an error. He could have easily found some fragments of chems that would have helped him. He is insanely smart and knows he needs the to stay that way.

There's absolutely no reason not search the entire area for the needed chems when he knows what will happen to him once he's off them.

But, maybe he was concerned they'd send another drone to double up on the job since they did have some issues "killing" him. So it could just be that his brains survival instinct kicked in more than his need for chems, but I never bought it in the film.