addTiddler = (tiddler, isForce) => {

  let tObj = getTiddler(tiddler);

  if (!isForce && tObj) {
    return tObj;
  }

  tObj = new $tw.Tiddler(
    {
      title: tiddler,
      text: ''
    },
    $tw.wiki.getModificationFields(),
    $tw.wiki.getCreationFields()
  );

  $tw.wiki.addTiddler(tObj);

  return tObj;

}
Advanced addTiddler method.

It adds timestamps and only adds the tiddler if it doesn't exist
yet or the force option is used.

This method is guarded against
https://github.com/Jermolene/TiddlyWiki5/issues/2025