title: Incorrect value for stdio stream: WriteStream
body: <pre><code>const barStream = fs.createWriteStream('bar');
  const foo = spawn('foo', [], { stdio: ['ignore', barStream, 'inherit'] });
  </code></pre>
  
  <p>throws an error:</p>
  
  <blockquote>
    <p>Incorrect value for stdio stream: WriteStream</p>
  </blockquote>
  
  <p>Doing this in reverse like <code>foo.stdout.pipe(barStream)</code> likely does the trick in some cases.</p>
  
  <p>But why exactly <code>WriteStream</code> cannot be supplied as stdout stream? Is there a way to make <code>barStream</code> suitable for stdout?</p>