Updating previous question with detailed example. I have a google sheet with three used columns (A: Event Title, B: Event Description, and D: Event Date). I want to create a new all day event on Google Calendar if none exists, and update the existing one if it already exists.

Here is the code I tried: I am getting the error: TypeError: Cannot read property 'setDescription' of undefined

function updatecal(){
  var cal = CalendarApp.getCalendarById('c_lmsj3r1ogsaafhc68gfalstdco@group.calendar.google.com');
  var data = SpreadsheetApp.getActive().getSheetByName("Data For Calendar");
  const rows = data.getDataRange().getValues();
  rows.forEach(function(row, index){
    if (index === 0) return;
    var eventdate = data.getRange(index, 4, 1, 1).getValue();
    var eventtitle = data.getRange(index,1,1,1).getValue();
    var eventdescription = data.getRange(index,2,1,1).getValue();
    console.log(eventdate + eventtitle + eventdescription)
    const eventdate1 = new Date(eventdate)
    const events = cal.getEventsForDay(eventdate1);
    if (events.lenght == 0){
      var newevent = cal.createAllDayEvent(eventtitle,eventdate1,
    {description: eventdescription});
    } else {
      ev = events[0];
      ev.setDescription(eventdescription)
    }

  })

}