通知作成時にpackしてnullになったらあとの処理をやめる

packages/backend/src/core/NotificationService.ts

@@ -155,6 +155,8 @@ export class NotificationService implements OnApplicationShutdown {
 
 		const packed = await this.notificationEntityService.pack(notification, notifieeId, {});
 
+		if (packed === null) return null;
+
 		// Publish notification event
 		this.globalEventService.publishMainStream(notifieeId, 'notification', packed);