12:59:43 PM: error "gatsby-source-prismic" threw an error while running the sourceNodes lifecycle:
12:59:43 PM: Unexpected status code  on URL https://matteo-dirollo.prismic.io/api/v2?access_token=undefined
12:59:43 PM: not finished source and transform nodes - 0.254s
You are missing some kind of access token here. I can’t tell you exactly how to fix it, but this is the source of your error. Do you need to have the access token in an environment variable, maybe?