Ok got it
I had to change a little bit of code in the mapper.js file where Alex wrote (line 10):
slice.items.map(async (item) => {
I had to change it for the new Repeatable Group like this:
slice.primary.items.map(async (item) => {
Now it's working!
I hope I can help others with this
@alex.trost thanks for your tutorials with sveltekit, I'm having fun following them
Paul