tree組件報(bào)錯Cannot read property 'key' of null

渲染TreeNode的時候報(bào)錯Cannot read property 'key' of null，但是key值我已經(jīng)賦值了，我如果換成普通span標(biāo)簽是可以渲染出來值的，這個報(bào)錯是什么原因呢

treeNode = (list, treeData) => {
    if (list) {
      return treeData.map((data) => {
        for (var i = 0; i < list.length; i++) {
          if (data.key == list[i].id) {
            return <TreeNode title={data.label} key ={data.key}></TreeNode>
          }
        }
      })
    }
};

<Tree
    checkable
    onSelect={this.onSelect}
    onCheck={this.onCheck}
 >
    {this.treeNode(list, treeData)}
</Tree>