title: I'm getting error code #100 and subcode #2018034 for my messenger bot
body: <p>I'm trying to build a messenger bot. but I'm getting following error. the provided message is just a simple text to test the bot. I'm building this for the first time with wit.ai. please help!</p>
  <pre><code>error: {
  message: '(#100) Message cannot be empty. A ' +
  'valid attachment or text must be ' +
  'provided.',
  type: 'OAuthException',
  code: 100,
  error_subcode: 2018034,
  fbtrace_id: 'A-3ZQ5XugMW6FTbM6ttwE1R'
  }
  </code></pre>