title: Openlayers - Get 404 when calling json file
body: <p>I've a simple local openlayer application via npm on localhost:1234 running. </p>
  
  <p>I trying to use the workshop Example: <a href="http://openlayers.org/workshop/en/vector/geojson.html" rel="nofollow noreferrer">http://openlayers.org/workshop/en/vector/geojson.html</a></p>
  
  <p>But I get always "featureloader.js:102 GET <a href="http://localhost:1234/data/countries.json" rel="nofollow noreferrer">http://localhost:1234/data/countries.json</a> 404 (Not Found)" </p>
  
  <p>My json file is for sure found on workshop/data/countries.json. </p>
  
  <p>Why do I get an 404 error?</p>