ScriptProperties Gotcha in Google Apps Script

For reasons of insanity I have wrapped the ScriptProperties of the PropertiesService in a object with get, set, forget and getKeys methods, viz:

function ScptProps() {
  this.scriptProperties = PropertiesService.getScriptProperties();
}

ScptProps.prototype.get = function (name) {
  return this.scriptProperties.getProperty(name);
};

ScptProps.prototype.set = function (name, value) {
  return this.scriptProperties.setProperty(name, value);
};

ScptProps.prototype.forget = function (name) {
  return this.scriptProperties.deleteProperty(name);
};

ScptProps.prototype.getKeys = function () {
  return this.scriptProperties.getKeys();
};

Using the REPL from my previous posting, I issued the following commands:

(new ScptProps).set('goose',58);
typeof (new ScptProps).get('goose');
(new ScptProps).forget('goose');

Goose is me and 58 my age for those interested.

And the gotcha? Well, I was a little taken aback recently, while debugging a number to number comparison issue, to discover that when I store a number I don't get one back. I get a string back and have to do a parseInt() on it to get its original value. The result of typeof (new ScptProps).get('goose'); is, you guessed it, string!