code: function condMerge(arg) {
      var args = arg.filter(function (v) {
          return !!v;
      });
      if (args[0] && args[0].empty && args.length > 1) {
          delete args[0].empty;
      }
      return _mergeOptions2.default.apply(undefined, _toConsumableArray(args));
  }
docs: TODO: figure out where error events originate (storage or model) and who keeps a roll-backable delta