vite + vue TypeError: 정의되지 않은 속성을 읽을 수 없습니다(‘checkedNumbers’ 읽기).

<script setup> import { computed, ref, watch } from "vue"; let checkedNumbers = ref([]);
function sum(){
return this.checkedNumbers.reduce(function (a, b) {
return parseFloat(a)+ parseFloat(b);
},0); }

<span id="prixSum" class="sm:text-center lg:text-left block font-bold text-sky-500 text-xl font-semibold lg:text-left">
{{ prixSum = sum()== 0 ? model.prixS1 : parseFloat(sum()+ model.prixS1).toFixed(2) }}
</span> <ul>
<li> <span
class="px-5 py-3 font-semibold text-sm tracking-wider bg-blue-500
text-center rounded dark:bg-indigo-700
dark:text-gray-900">{{model.prixS1}} </span>
<input type="checkbox" id="model.prixS2" name="model.prixS2" v-model="checkedNumbers"
:value="model.prixS2"
class="hidden peer" required>
<input type="checkbox" id="model.prixS3" name="model.prixS3" v-model="checkedNumbers"
:value="model.prixS3"
class="hidden peer" required>
</li> </ul>