.idjs script, UXPScript Error! Error String: app is not defined

I'm trying to learn to use .idjs and I keep runing into the error: UXPScript Error! Error String: app is not defined. It's a very simple script to test and I think it should work but it doesn't. Anyone have any guidence. 

let myInDesign = require("indesign");
let myDoc = myInDesign.app.activeDocument;
let myLayer = myDoc.layers.item("Layer 1");

  if (!myDoc.layers.itemByName("DIGITAL").isValid) {
    myDoc.layers.add({ name: "DIGITAL" });
  }

  if (myDoc.layers.itemByName("Layer 1").isValid) {
  myLayer.remove();
  }