fixing typo

src/reducers/cart.ts

@@ -30,7 +30,7 @@ const cartReducer = (state = initialState, action: CartActionTypes) : CartState
       }
     case VIEW_CART:
       return {
-        // sort without mutating mutating the previous state
+        // sort without mutating the previous state
         products: state.products.slice().sort(sortByTitle),
       }
     case CHECKOUT_CART: