npm rejects a bare _auth key (ERR_INVALID_AUTH) against a private registry; derive the host from NPM_REPO_URL and write //<host>/:_auth=<base64> instead.
npm rejects a bare _auth key (ERR_INVALID_AUTH) against a private registry; derive the host from NPM_REPO_URL and write //<host>/:_auth=<base64> instead.