FIX: add support for default title in localdates (#36511)

When clicking "Add to calendar" in chat we would error out cause title
was
null.

config/locales/client.en.yml

@@ -5117,6 +5117,7 @@ en:
       add_to_calendar: "Add to calendar"
       google: "Google Calendar"
       ics: "ICS"
+      default_title: "Scheduled Event"
     tagging:
       all_tags: "All tags"
       other_tags: "Other Tags"

frontend/discourse/app/lib/download-calendar.js

@@ -2,12 +2,13 @@ import downloadCalendarModal from "discourse/components/modal/download-calendar"
 import { getOwnerWithFallback } from "discourse/lib/get-owner";
 import getURL from "discourse/lib/get-url";
 import User from "discourse/models/user";
+import { i18n } from "discourse-i18n";
 
 export function downloadCalendar(title, dates, options = {}) {
   const currentUser = User.current();
 
   const formattedDates = formatDates(dates);
-  title = title.trim();
+  title = (title || i18n("download_calendar.default_title")).trim();
 
   switch (currentUser?.user_option.default_calendar) {
     case "ics":