Need help getting fullCalendar to display

I am trying to create a custom element which displays the FullCalendar node module.

The NPM package was successfully installed through the Corvid package manager.

I then created a custom element in Corvid, with the code below in the JavaScript file for that custom element, which has a tag of wix-calendar. However when I load the page in the browser, nothing appears, and I get no errors in the console.

Any ideas as to what I am doing wrong? Many thanks for any assistance you might be able to provide.

import { Calendar } from "fullcalendar";
import dayGridPlugin from "@fullcalendar/daygrid";
const DEBUG_TEXT = 'Loading the code for Custom Element \'wix-default-custom-element\'. ';

const createCalendarContainer = () => {
  const calendarContainer = document.createElement('div');
  calendarContainer.id = 'calendar';
  return calendarContainer;
};

document.addEventListener('DOMContentLoaded', function() {
  var calendarEl = document.getElementById('calendar');

  var calendar = new Calendar(calendarEl, {
    plugins: [ dayGridPlugin ]
  });

  calendar.render();
});

class WixFullCalendar extends HTMLElement {
  constructor() {
    super();
    console.log(DEBUG_TEXT);
  }

  connectedCallback() {
    this.appendChild(createCalendarContainer());
  }
}
customElements.define('wix-calendar', WixFullCalendar);
https://www.youtube.
com/watch?v=MKo5AFupDQg