"Uncaught SecurityError: Blocked a frame with origin "null" from accessing a frame with origin "null". Protocols, domains, and ports must match."

var myapp.story1 = "Complete text of story1.txt"

fetch("./config.json").then(function(res) {
    // res instanceof Response == true.
    if (res.ok) {
      res.json().then(function(data) {
        console.log(data);
      });
    } else {
      console.log("Looks like the response wasn't perfect, got status", res.status);
    }
  }, function(e) {
    console.log("Fetch failed!", e);
  });