Migrate Notifications interface patterns

src/govoplan_notifications/backend/service.py

@@ -322,6 +322,10 @@ def update_notification(
         notification.read_at = notification.read_at or now
         notification.acknowledged_at = notification.acknowledged_at or now
     elif payload.status == "cancelled":
+        if notification.status not in PENDING_STATUSES | {"paused"}:
+            raise NotificationError(
+                f"Notification cannot be cancelled from status {notification.status}"
+            )
         notification.status = "cancelled"
         notification.cancelled_at = notification.cancelled_at or now
     if payload.metadata is not None: