Yeah, I don't know how you mess that up.
OK, you might have -more- veggies than I like; or -not enough- for my tastes. But it's not like it's going to be awful.
I guess you could cook it way too long, so that the veggies are mush--but then, you just mush them up, stir them in, and call it a thick soup.
If you undercook them, just call it crunchy soup.