Child directly nested in route. Riot.js v4

app.riot

<app>
  <h1>Hello</h1>
  <router>
    <ul>
      <li>
        <a href="/child">Child</a>
      </li>
    </ul>
    <route path="/child">
      <child something={ doSomething }></child>
    </route>
  </router>
  
  <script>
    export default {
      doSomething(thing) {
        console.log(thing)
        this.update()
      }
    }
  </script>
<app>

child.riot

<child>
  <h2>Hello from child</h2>
  
  <script>
    export default {
      onMounted(props, state) {
        props.something('child')
      }
    }
  </script>
</child>