anchor.diff:    Instead of adding the `"/sidekicks"` route, define a `wildcard` route instead and have it navigate to a simple `PageNotFoundComponent`.
     
     不要添加`"/sidekicks"`路由，而是定义一个"通配符"路由，让它直接导航到`PageNotFoundComponent`组件。
  -  
  +
   +makeExcerpt('src/app/app.module.1.ts', 'wildcard')
   
   :marked
     Create the `PageNotFoundComponent` to display when users visit invalid URLs.
     
     创建`PageNotFoundComponent`，以便在用户访问无效网址时显示它。
  -  
  +
   +makeExcerpt('src/app/not-found.component.ts (404 component)', '')
   
   :marked
  
positive.code:   you should see something like the following URL in the browser address bar.
  
  code-example.
      http://.../crisis-center(popup:compose)
  
  :marked
    The interesting part of the URL follows the `...`:
  
negative.code: 
  
  .l-main-section
  
  a#basics
  :marked
    ## The Basics
  