v-contextmenu 報(bào)錯(cuò)ref未定義求解

報(bào)錯(cuò) [Vue warn]: Error in directive contextmenu bind hook: "TypeError: Cannot read property '$refs' of undefined"

  <div :class="['box', theme]" v-contextmenu:contextmenu>
    <Tree :data="data1" @on-select-change="treeChange"></Tree>
  </div>
  <v-contextmenu :theme="theme" ref="contextmenu">
    <v-contextmenu-item>菜單1</v-contextmenu-item>
    <v-contextmenu-item>菜單2</v-contextmenu-item>
    <v-contextmenu-item>菜單3</v-contextmenu-item>
  </v-contextmenu>
  
  
  
  import Vue from 'vue'
  import contentmenu from 'v-contextmenu'
  import 'v-contextmenu/dist/index.css'
  import Contextmenu from 'v-contextmenu'
  import ContextmenuItem from 'v-contextmenu'
  Vue.use(contentmenu)
  

求別貼源碼地址了。。。我已經(jīng)翻了很多遍了。。謝謝大佬們。。。