在Vue2.0 使用v-for时报这样的错误：component lists rendered with v-for should have explicit keys.解决方法：

在vue2.0+element-ui时的v-for  报了一个这样错误：

(Emitted value instead of an instance of Error) <el-tag v-for="tag in getHasRoles(scope.row.superrole)">: component lists rendered with v-for should have explicit keys.(Emit