gulp serve blanc page

Hi, I’m new to developing and trying to set up a development environment on my Mac.
So far the commands are working, but ‘gulp serve --theme=“volumio”’ gives me a blank webUI page in my browser.
I just pulled the image so that should be a recent version.
The local-config.json file holds the URL of my RPi with Volumio.

Any advise on how to get this working?

thanks in advance,