message: Fix minor semantic error
diff: @@ -62,7 +62,7 @@ lectureSchema.methods.exportJSON = async function() {
  obj.units = await Promise.all(units.map((unitId: mongoose.Types.ObjectId) => {
  return Unit.findById(unitId).then((unit: IUnitModel) => {
  - if (Unit) {
  + if (unit) {
  return unit.exportJSON();
  } else {
  winston.log('warn', 'unit(' + unitId + ') was referenced by lecture(' + this._id + ') but does not exist anymore');
  