On your web page: Get Started with GoJS, I created index.html as`
GoJS Greetings<script src="https://cdnjs.cloudflare.com/ajax/libs/gojs/1.6.15/go-debug.js"></script>
<script src="greetings.js"></script>
`
and greetings.js as var $ = go.GraphObject.make; var myDiagram = $(go.Diagram, "myDiagramDiv");
When it runs, it throws an: “Uncaught Error: Invalid DIV id; could not get element with id: myDiagramDiv”
This is not a good start. Please advise so I can follow your tutorial.