title: How to find which promises are unhandled in Node.js UnhandledPromiseRejectionWarning?
body: <p>Node.js from version 7 has async/await syntactic sugar for handling promises and now in my code the following warning comes up quite often: </p>
  
  <pre><code>(node:11057) UnhandledPromiseRejectionWarning: Unhandled promise 
  rejection (rejection id: 1): ReferenceError: Error: Can't set headers 
  after they are sent.
  (node:11057) DeprecationWarning: Unhandled promise rejections are 
  deprecated. In the future, promise rejections that are not handled 
  will terminate the Node.js process with a non-zero exit code.
  </code></pre>
  
  <p>Unfortunately there's no reference to the line where the catch is missing.
  Is there any way to find it without checking every try/catch block?</p>