Error in render: "TypeError: Cannot read property 'category_name' of undefined"

错误提示
[Vue warn]: Error in render: "TypeError: Cannot read property 'category_name' of undefined"

问题场景

<picker @change="bindPickerChange" :value="index" :range="category" range-key="category_name">  
   {{category[index].category_name}}  
</picker>

这里category初始值是 category：[]
需要在给初始值时，写成
category:[
{category_id:"",category_name:''}
],

使用 {{category[index].category_name}} 时就不会出错了