Detect when the Nextcloud server doesn't have the Notes app installed

My Nextcloud server didn't have the notes app installed. I forgot I had turned it off, and when launching Iotas via a terminal, I got the following output

thib@pc-20 ~> flatpak run org.gnome.World.Iotas
21:51:10 | sync_result | WARNING | Failed to decode server JSON response: Expecting value: line 1 column 1 (char 0)
21:51:10 | sync_manager | INFO | Refresh failed with status code None
21:51:10 | nextcloud_sync_worker | WARNING | Couldn't access version elements in server capabilities response. Is the Nextcloud Notes app installed within Nextcloud?
21:51:13 | sync_result | WARNING | Failed to decode server JSON response: Expecting value: line 1 column 1 (char 0)
21:51:13 | sync_manager | INFO | Refresh failed with status code None
21:51:13 | sync_manager | INFO | Flagging offline

After installing the app, I could sync my notes without a problem.

It seems to be possible to detect that the Nextcloud Notes app is not installed. It would be useful for the end user to display it.