【1】Error in v-on handler (Promise/async): “Error: Request failed with status code 500“

【2】[Vue warn]: Error in v-on handler (Promise/async): “TypeError: Object(…) is not a function“

【3】v-if判断控制子组件销毁与创建
【4】获取不到接口数据？竟然是因为忘记写return？