Ensure task UID to be treated as string

Allows to use all numeric UIDs, closes #394

Signed-off-by: Raimund Schlüßler <raimund.schluessler@mailbox.org>

src/store/calendars.js

@@ -45,7 +45,7 @@ const calendarModel = {
 	enabled: true,
 	owner: '',
 	shares: [],
-	tasks: [],
+	tasks: {},
 	url: '',
 	readOnly: false,
 	dav: false,
@@ -72,7 +72,7 @@ export function mapDavCollectionToCalendar(calendar) {
 		enabled: calendar.enabled !== false,
 		owner: calendar.owner,
 		readOnly: !calendar.isWriteable(),
-		tasks: [],
+		tasks: {},
 		url: calendar.url,
 		dav: calendar,
 		supportsTasks: calendar.components.includes('VTODO'),