Diagram doesn't show

I copied + pasted the code to run the diagram on Microsoft Expression as an HTML file. I save the file and try to view it on a browser. I see everything (text, border box) but the diagram itself. What am I missing?

Have you looked at any warning or error messages in the browser’s debugging console window?

that is what I get

Well, those error messages seem self-explanatory. You really do need to load go.js, although I recommend loading go-debug.js during development.

And you don’t need to load goSamples.js, because that is just used by the samples framework on https://gojs.net.