Concern over whether roast chicken is safe

The only way to know if your chicken is safe to eat is to measure its temperature. You should check the breast (165F/74C) and the thigh (can go higher than breast), ensuring your are measuring at the center and not touching bone. Stuffing is usually not a good idea, because it increases the cooking time, and will likely result in overcooked white meat or under cooked items in the cavity. Invest in a good thermometer and learn how to use it correctly, you will feel more comfortable and produce better meals.

Stuffing vegetables you intend to consume in the cavity of a chicken is generally a bad idea. By the time the vegetables are cooked, the chicken will be extremely overcooked. Moreover, since the vegetables have been in contact with raw chicken, all of them should reach a safe temperature for chicken (at least on the outside) before they're consumed. And making sure everything in the centre is cooked to a safe temperature makes the meat overcooked. So I would say that the chicken is probably fine, but you shouldn't eat the potatoes. If you want roast potatoes to go with it, cook them on a separate tray in the oven.