If you go onto the leaf extension and look at your profiles do you have the swi-vscode-support_190424 package installed into your profile?
We are still in an alpha state and haven’t fully integrated the tools yet by default into the package (this is coming). It looks like you don’t have mkedit installed (one of the tools that vsCode relies on to create the system).
Your installed packages should look something like this (I’m on an internal version atm so the package name will be different then what you have for the main leaf package but you want to make sure that swi-vsode-support is added to your current profile):
And then try to reload the window.
I hope that helps, if not please provide a screenshot of your leaf profiles and I can see what the issue is.