Cannot read property '__k' of null - FullCalendar + Angular 11

I am using Full Calendar plugin for Angular 11. I keep getting the error "Cannot read property '__k' of null". Seems it is happening when calendar.render() is called. But can't get to the bottom of it. Any help is much appreciated.

This is my ts file:

export class FullCalendarComponent {
    public calendar: Calendar | undefined;
    calendarEl: any;

    calendarOptions: CalendarOptions = {

        slotMinTime: '07:00:00',
        slotMaxTime: '19:00:00', 
        slotDuration: '00:15:00',
        height: 680,
        events: [

        headerToolbar: {
            start: 'today prev,next',
            center: 'title',
            right: 'dayGridMonth,timeGridWeek,timeGridDay,listWeek'
        firstDay: 1,
        initialView: 'timeGridWeek',
        weekends: true,
        editable: true,
        selectable: true,
        selectMirror: true,
        dayMaxEvents: true,
        select: this.handleDateSelect.bind(this),
        eventClick: this.handleEventClick.bind(this),
        allDaySlot: false,

    ngOnInit(): void {

        let calendarEl = document.getElementById('calendar');
        let calendar = new Calendar(calendarEl!, this.calendarOptions);


And my html file

  <div class="calendar">
        <full-calendar #calendar [options]="calendarOptions"></full-calendar>

Here is a screenshot of the error:

1 answer