title: Uncaught TypeError: (0 , o.default) is not a function: What's causing it?
body: <p>In my create react app project I'm running into the following error in my production build (not in my dev build):</p>
  
  <blockquote>
    <p>Uncaught TypeError: (0 , o.default) is not a function
        at Object.e.f.(:4444/anonymous function)...</p>
  </blockquote>
  
  <p>I've been investigating this bug for a couple of hours but struggle to find out how to debug this uglified piece of js. </p>
  
  <p>What makes it tough is that the error returns <strong>o</strong>.default and not <strong>SomeLibrary</strong>.default so I don't really know where to start my search really...</p>
  
  <p>What does that <strong>o</strong>.default mean in this case? Any tips for figuring out what's going wrong here?</p>