Получаю NaN в переменную totalPrice (React.js)

Не могу разобраться как избавиться от NaN в totalPrice.

При добавлении товара в корзину onClick={onClickAdd} в переменной {totalPrice} получаю NaN.

Компонент Control.jsx

function Control() {
   const { items, totalPrice } = useSelector(selectCart);

   const totalCount = items.reduce((sum, item) => sum + item.count, 0);

   return (
      <ul className="header__top-right">
         <li>
            <NavLink to="/cart">
               <span>{totalPrice} $</span>
               <img src={cart} alt="cart" />
               <span>{totalCount}</span>
            </NavLink>
         </li>
      </ul>
   )
}

Страница карточки товара FullCoffee.jsx

function FullCoffee({ imageUrl, alt, title, price, weights }) {
   const [coffee, setCoffee] = React.useState();
   const { id } = useParams();

   const dispatch = useDispatch();
   const cartItem = useSelector(selectCartItemById(id));

   const onClickAdd = () => {
      const items = {
         id,
         title,
         price,
         imageUrl,
         alt,
      };
      dispatch(addItem(items));
   };

   return (
      <div className="full__coffee">
         <div className="wrapper">
            <Control />
            <div className="full__coffee-container">
               <h3 className="full__coffee-title">{coffee.title}</h3>
               <div className="full__coffee-flex">
                  <button onClick={onClickAdd} className="button>
                     Add</button>
               </div>
            </div>
         </div>
      </div>
   )
}

cartSlice.js

export const cartSlice = createSlice({
   name: 'cart',
   initialState,
   reducers: {
      addItem(state, action) {
         const findItem = state.items.find(obj => obj.id === action.payload.id);

         if (findItem) {
            (findItem.count)++;
         } else {
            state.items.push({
               ...action.payload,
               count: 1,
            });
         }

         state.totalPrice = state.items.reduce((sum, obj) => {
            return obj.price * obj.count + sum;
         }, 0);
      },
   },
});