ExtendScript Debugger Visual Studio Code Link to Photoshop App

I am trying out scripting Photoshop, I am experienced using Visual Studio but not the code version, I have also written in Javascript many times but the environment around using VS Code and the ExtendScript Debugger is causing me issues.  I'm using ExtendScript Debugger with VS Code 1.85.1, running under Windows 10.  I've run scripts directly from Photoshop and they have worked, however, I want to use the debugger running in Visual Studio Code and have been following tutorials from various sources. I'm just testing to see that I can link to Photoshop and get some basic information back about layers. The following is my code so far:

main();
function main(){
   alert("Hello");
   var doc=app.activedocument;
   var myWindow = new Window("palette","My Window",undefined);
   myWindow.orientation="row";

This launches ok and pops up an alert window in Photoshop. But is then should pop up a window but doesn't. There are no errors, however, intellisense does not have app and the code app.activedocument appears to be ignored. I have also not been able to find myWindow.show() which I think is what will display to window. Possibly I have missed a step in setting up VS Code.