stylelint-bundle-worker.js
function isCharClass(a, b, step, isNum, isDescending) {
  if (isDescending) { return false; }
  if (isNum) { return a <= 9 && b <= 9; }
  if (a < b) { return step === 1; }
  return false;
}
function isCharClass(a, b, step, isNum, isDescending) {
  if (isDescending) { return false; }
  if (isNum) { return a <= 9 && b <= 9; }
  if (a < b) { return step === 1; }
  return false;
}
Check for invalid characters