title: Can I specify how to handle errors in the async javascript library?
body: <p>I'm trying to sanitize inputs for an asynchronous function. Specifically, given a list of credentials for an API, I'm trying to filter out which ones are invalid by sending a test request to the API and examining the result for each one.</p>
  
  <p>The problem I'm facing is this: I would like to collect the invalid keys into a single list. I would normally use the <code>async</code> library to execute the requests in sequence, using the <code>series</code> function. But, from the documentation:</p>
  
  <blockquote>
    <p>If any functions in the series pass an error to its callback, no more functions are run, and <code>callback</code> is immediately called with the value of the error.</p>
  </blockquote>
  
  <p>This isn't the desired behavior: I want to collect the errors in place of the responses (or both of them). Is this possible, using this library, without changing the way I'm interacting with the API?</p>