I get this error when try to discard change of new appointment on outlook online

Question

I got a Uncaught (in promise) TypeError

When I try to:

• go to outlook online https://outlook.office365.com/ > calendar > select datetime
• open new appointment window > set Repeat = Every day
• open my add-in > a task pane with my add-in content shown
• close new appointment window & try to discard change
• then I get this message There was something that went wrong with the application. Please refresh your browser window to continue.
• I inspect & found this Uncaught (in promise) TypeError: Cannot read property 'IsMeeting' of null from this code eventToDelete.IsMeeting && responseSent && !eventToDelete.IsCancelled here

this is the fullpath to the file cause the error that I can find owa/./packages/common/controls/packages/calendar/data/owa-calendar-event-notification-bar/lib/utils/showUndoNotificationForInstantDelete.ts

UPDATE: I will not face this error if I comment out the code that set custom property like this

let customProperties: Office.CustomProperties;
if (this._appointment.CustomUid && this._appointment.CustomUid != '') {
    //customProperties.set(this._customUidKey, this._appointment.CustomUid);
    //customProperties.saveAsync();
}

Then I think this is a bug of OWA while handle recurring appointment with custom property, right?

Appreciate all your help.