As stated above, this is a recipe for a slightly sweeter and slightly less bean-y chili. Feel free to up the beans to two cans if you like, and feel free to decrease the sugar or omit altogether if that’s your preference.
As for the chocolate, David Lebovitz recommends unsweetened chocolate for this, which I did not have. If you use this instead, you might want to increase the amount of brown sugar to compensate.