function modeNum(mode) {
  // eslint-disable-next-line no-self-compare
  if (typeof mode === 'number' && mode === mode) // Valid, non-NaN number
    return mode;
  if (typeof mode === 'string')
    return modeNum(parseInt(mode, 8));
  throw new Error(`Cannot parse mode: ${mode}`);
}
The software constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.