How can components of a packaged food item exceed the net weight?
As Zanna said, you can't just add all the values together, some items are a fraction of others.
In this case, "total carbohydrates" already includes the "sugar" and "dietary fibre" items, so the total is "fat" + "total carbohydrates" + "protein", which adds up to 27g out of 30g. That leaves 3 g for water, ash (inorganic salts, like table salt, basically) and minor components (like vitamins). 

But keep in mind that all those values are rounded to the nearest whole number, which causes the energy stated to be different from that obtained from the ingredients weights.