Updated Drupal to 8.6. This goes with the following updates because it's possible...

[yaffs-website] / node_modules / underscore.string / helper / strRepeat.js

module.exports = function strRepeat(str, qty){
  if (qty < 1) return '';
  var result = '';
  while (qty > 0) {
    if (qty & 1) result += str;
    qty >>= 1, str += str;
  }
  return result;
};