解决[Vue warn]: Invalid prop: custom validator check failed for prop “index“的问题

解决方法：:index里面呢的 index的值不能有空格，并且要为字符串类型，然后在后面加上.toString()

<el-menu
                :default-active="this.$route.path"
                class="el-menu-demo menuNav scroll-menu"
                mode="horizontal"
                background-color="#FFFFFF"
                style="border-top: none"
                text-color="#444645"
                active-text-color="#444645"
              >
                <div class="menuWidth">
                  <el-menu-item
                    class="updateRedFont"
                    :index="1 + index.toString()"
                    v-for="(item, index) in menuData"
                    :key="index"
                    @click="active = index"
                  >
                    {{ item.sysMenuName }}
                  </el-menu-item>
                </div>

                <el-submenu index="2">
                  <template slot="title">更多</template>
                  <el-menu-item
                    class="updateRedFont"
                    :index="1 + index.toString()"
                    v-for="(item, index) in menuData"
                    :key="index"
                    @click="active = index"
                  >
                    {{ item.sysMenuName }}
                  </el-menu-item>
                </el-submenu>
                
              </el-menu>