Can't convert empty array..

<Header.js>
--
--
--
--
{/*Right Side Menu  */}
            <div className="rightMenu">
               {auth.authenticate ? renderLoggedInMenu() : renderNonLoggedInMenu()}
               <DropDownMenu
                  menu={
                     <a className="more">
                        <span>More</span>
                        <IoIosArrowDown />
                     </a>
                  }
                  menus={[
                     { label: "Notification Preference", href: "", icon: null },
                     { label: "24x7 Customer care", href: "", icon: null },

                  ]}
               />
               <div>
                  <a href={`/cart`} className="cart">
                     <Cart count={Object.keys(cart.cartItems).length} />
                     <span style={{ margin: "0 10px" }}>Cart</span>
                  </a>
               </div>
            </div>
            {/* right side menu ends here */}
         </div>
      </div>
   );
};

export default Header;

<cart.reducer.js>
import { cartConstants } from "../actions/constants";

const initState = {
    cartItems:{

    },
    updatingCart:false,
    error:null
}

export default (state = initState, action) => {
    switch(action.type){
        case cartConstants.ADD_TO_CART_REQUEST:
            state ={
                ...state,
                updatingCart:true
            }
            break;

         case cartConstants.ADD_TO_CART_SUCCESS:
             state ={
                 ...state,
                 cartItems:action.payload.cartItems,
                 updatingCart:false
             }
             break;

         case cartConstants.ADD_TO_CART_FAILURE:
             state ={
                 ...state,
                 updatingCart:false,
                 error:action.payload.error
             } 
             break;   
             
         case cartConstants.RESET_CART:
             state ={
                 ...initState
             }    
            break;
    }
     return state;
}