Right now it's possible for metalsmith-permalinks to try to create folder outside the current directory of the project, as mentioned in this issue. I think this is the error pointed out in #3, since I was having the same one and was able to fix it with this.
You might only see this issue if .use(markdown()) comes before .use(permalinks({...})), but given that project doesn't provide any safety against it, I think this is still a good safety check!
Right now it's possible for metalsmith-permalinks to try to create folder outside the current directory of the project, as mentioned in this issue. I think this is the error pointed out in #3, since I was having the same one and was able to fix it with this.