title: Flowtype function can throw error
body: <p>Is there any way to define that a function explicitly can throw, obviously any function can throw an error. But I'd like to explicitly define that a function is designed to throw and possibly not return a value at all.</p>
  
  <pre><code>async function falseThrow (promise: Promise&lt;any&gt;, error): any {
    let value: any = await promise
    if (!value) throw error
    return value
  }
  </code></pre>