title: How to delete a key with lodash _.map
body: <p>I have a lodash map function that sometimes has an empty value in the important property of a given key, and in this case I'd like to remove that key from the result entirely. How do I do that?</p>
  
  <p>Tried just <code>if (_.isEmpty(key.thing)) { delete key }</code> but this didn't work - it actually broke the app.</p>