@gerardcsaperas, the error says that you have files, perhaps it’s not loading properly for this time. You can close the browser and reopen or check it again in few hours or leave it as it is, and start again with new files- fork again.
This happens to me, every now and again. I think it has something to do with slow internet. The only thing that works for me is to close the project, and click on the link to create another boilerplate.