Мерзавец игнорирует файл для проектов C

new Vue({
 el: "#app",
 data: {
   checked: [],
   activeList : {listItems:[1,2,3,5]}
 },
 created: function() {
   for(var i = 0; i < this.activeList.listItems.length; i++) {
     this.checked.push(false);
   }
 },
 methods: {
  checkTaskDone(item) {
   if (this.checked[item] == false) {
    this.$set(this.checked,item, true);
   } else if (this.checked[item] == true) {
    this.$set(this.checked,item, false);
   }
  }
 }
 });

.checked {
 text-decoration: line-through;
 color: red;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
<div v-for="(listItem, index) in activeList.listItems" :key="index" :class="{checked: checked[index]}">
 {{ index+1 }}. {{ listItem }}
  <span @click="checkTaskDone(index)">
    <i class="f7-icons" id="check-task-btn">check_round</i>
  </span>
</div>

</div>