code: function onError(err) {
      err.usage = 'tar -cvz . | curl -sSNT- HOST/deploy/USER/APP';
      err.blame = {
        type: 'system',
        message: 'Unable to unpack tarball'
      };
      return callback(err);
    }
docs: Handle error caused by `zlib.Gunzip` or `tar.Extract` failure