控制台输出警告：
Named Route 'user' has a default child route. When navigating to this named route (:to="{name: 'user'"), the default child route will not be rendered. Remove the name from this route and use the name of the default child route for named links instead.
即：
命名路由“user”具有默认子路由。导航到此命名路由（：to=“{name:”user“）时，将不会呈现默认子路由。从该路由中删除该名称，并改用命名链接的默认子路由的名称。
说明对有子路由的路由使用命令路由时，子路由失效。
