Vue解决warning Emitted value instead of an instance of Error

避免Emitted value instead of an instance of Error，
这部分在运行的时候就会出现问题

<el-submenu v-for="(item,index) in datalist"   :index="index.toString()+1" v-if="item.children.length===0">
                <template slot="title">
                    <i   :style="{color:item.icocolor}" :class="item.ico">i>
                    <span slot="title">{{item.name}}span>
                template>
                <el-menu-item :index="index.toString()+1" v-on:click="toOpen(item.pathname)">{{item.name}}el-menu-item>
            el-submenu>

问题图片如图：

参考：https://blog.csdn.net/twinkle2star/article/details/73741120  后确实避免了warning
以下部分是没有问题的
<el-submenu v-for="(item,index) in datalist"  :key="index" :index="index.toString()+1" v-if="item.children.length===0">
                <template slot="title">
                    <i   :style="{color:item.icocolor}" :class="item.ico">i>
                    <span slot="title">{{item.name}}span>
                template>
                <el-menu-item :index="index.toString()+1" v-on:click="toOpen(item.pathname)">{{item.name}}el-menu-item>
            el-submenu>