Non-expiring grant/token

[AndreYurin]

Hi!

First of all, thank you for your work, helps a lot and works great!

I want to ask about the ttl settings: I see in the library types, in the examples, that setting “Grant” ttl to “undefined” is allowed and it should be considered as “exp will be missing when expiration is not configured on the Grant model”. I also see that checkTTL function allows undefined value:

checkTTL() {
    Object.entries(this.ttl).forEach(([key, value]) => {
      let valid = false;
      switch (typeof value) {
        case 'function':
          if (value.constructor.toString() === 'function Function() { [native code] }') {
            valid = true;
          }
          break;
        case 'number':
          if (Number.isSafeInteger(value) && value > 0) {
            valid = true;
          }
          break;
        case 'undefined': // does not expire
          valid = true;
          break;
        default:
      }

      if (!valid) {
        throw new TypeError(`ttl.${key} must be a positive integer or a regular function returning one`);
      }
    });
  }

But if I try to set it to “undefined”, it doesn't work - the ttl will have a function. This is because during configuration creation, here, there is an else if check that doesn't allow undefined values:

function merge(target, ...sources) {
  for (const source of sources) {
    if (!isPlainObject(source)) {
      continue;
    }
    for (const [key, value] of Object.entries(source)) {
      if (key === '__proto__' || key === 'constructor') {
        continue;
      }
      if (isPlainObject(target[key]) && isPlainObject(value)) {
        target[key] = merge(target[key], value);
      } else if (typeof value !== 'undefined') {
        target[key] = value;
      }
    }
  }

  return target;
}

If I remove esle if (typeof value !== 'undefined') and instead set it to just else, allowing undefined values, everything works fine.

So I was wondering: should we or shouldn't we have the ability to set ttl to undefined value and the logic to handle that? I would like to keep the Grant from expiring.

Thank you in advance!