van-checkbox-group horizontal is invalid

gistfile1.txt

    <van-cell-group title="标签">
      <van-checkbox-group value="{{ tags }}" bind:change="onChangeTags" direction="horizontal">
        <block v-for="(tagid, tagtitle) in tagList" :key="{{ tagid }}">
          <van-checkbox name="{{ tagid }}" shape="square">{{ tagtitle }}</van-checkbox>
        </block>
      </van-checkbox-group>
    </van-cell-group>