getNextFreq method Null safety

String getNextFreq(
  1. DateTime zerPoint
)

will return a string of the next date time of the frequency occureance

Implementation

String getNextFreq(DateTime zerPoint) {
  String retVal = "Couldn't Calculate Next Frequency Time";

  if (this.isOnce) {
    retVal = "Once";
  } else if (this.isDynamic) {
    retVal = getDynamicDate(this, zerPoint).toString();
  } else if (this.isStatic) {
    retVal = getStaticDate(this, zerPoint).toString();
  }

  return retVal;
}