Confused

Why is there sugar in my Vegetable Stock?

I went to make some rice and decided to use vegetable stock instead of water...you know, to impart more flavor.  So I went to the pantry and grabbed the Giada de Laurentis veggie stock that Matt had gotten on sale at Target.  It was really cheap; a deal he couldn't pass up.  And we figured it was Giada, so it had to be good.

It says it's all natural.  "a flavorful stock made from carrots, onion, celery, and sea salt."   I would have thought those were the ingredients...I mean, why would there be anything else, right?

And then I got to reading the rest of the box.

Ingredients: vegetable stock (water, vegetable flavor concentrate (vegetable juice concentrate [carrot, celeriac, onion], cooked vegetables [carrot, onion, celery], tomato paste, yeast extract, sea salt, cane sugar, molasses, onion powder, potato flour, natural flavor, canola oil)), cane sugar, sea salt.

Again, why is there sugar in my vegetable stock?  And yeast extract (whatever that is)?  And potato flour?  Why would you need potato flour?  Just use a freakin potato.  What constitutes "natural flavor" and where did it come from?

I think I'll be making my own from here on out...and canning it for convenience.  That way I'll know exactly what is (and isn't) in it.

Now I just need some jars and a pressure canner.  I found a tutorial here.  She also has a tutorial on vegetable bouillon which sounds interesting.