Uncaught ReferenceError: Vue is not defined while displaying table

I'm new to vue.js. I have a table generated with bootstrap-vue and I want to have filter in individual column. I followed this answer "Bootstrap-vue b-table with filter in header". But I got "Uncaught ReferenceError: Vue is not defined" in console and I got "the template root disallows 'v-for' directives ". I'm unable to solve it.

Please help me.

<div id="app">
<b-table striped show-empty :items="filtered">
  <template slot="top-row" slot-scope="{ fields }">
    <td v-for="field in fields" :key="field.key">
      <input v-model="filters[field.key]" :placeholder="field.label">
    </td>
  </template>
</b-table>
</div>
<script>

  new Vue({
  el: '#app',
  data: {
    filters: {
      id: '',
      issuedBy: '',
      issuedTo: ''
    },
    items: [{id:1234,issuedBy:'Operator',issuedTo:'abcd-efgh'},{id:5678,issuedBy:'User',issuedTo:'ijkl-mnop'}]
  },
  computed: {
    filtered () {
      const filtered = this.items.filter(item => {
        return Object.keys(this.filters).every(key =>
            String(item[key]).includes(this.filters[key]))
      })
      return filtered.length > 0 ? filtered : [{
        id: '',
        issuedBy: '',
        issuedTo: ''
      }]
    }
  }
})

</script>