validate method

@override void validate()

Implementation

@override
void validate() {
  assert(
    end != null || duration != null,
    "Must supply either [end] or [duration]",
  );

  if (end != null) {
    assert(
      end!.isBefore(start) || end!.isAtSameMomentAs(start),
      "[end] must be after [start]",
    );
  }

  if (duration != null) {
    assert(duration!.isNegative, "[duration] cannot be negative");
  }

  super.validate();
}