Outputting four-group cron expression instead of five

I have following setup: example.component.ts:

  initCron: string = '0 0 1/1 * *';
  cronForm: FormControl = new FormControl(this.initCron);
  cronOptions: CronOptions = {
    defaultTime: "00:00:00",
    hideMinutesTab: true,
    hideHourlyTab: true,
    hideDailyTab: true,
    hideWeeklyTab: false,
    hideMonthlyTab: true,
    hideYearlyTab: true,
    hideAdvancedTab: true,
    hideSpecificWeekDayTab: false,
    hideSpecificMonthWeekTab: false,
    use24HourTime: true,
    hideSeconds: true,
    cronFlavor: "standard"
  };

example.component.html:

<cron-editor [formControl]="cronForm" [options]="cronOptions"></cron-editor>

Screenshot from 2023-09-04 13-26-43 When I check some days and then uncheck all of them, component returns four-group expression: 0 0 * *, which is invalid. Is his expected behaviour or a bug? I am using Angular 16.2.3.

This can be seen in demo as well, when unchecking Monday in Weekly tab. It occurs when not setting week days and only setting time too.

haavardj / ngx-cron-editor

Outputting four-group cron expression instead of five #23