The errors while paused can probably be fixed even though they don’t really affect much at all. The ones from the first screenshot…
cast_sender.js will throw an error if chromecast extension isn’t installed. The error is printed by design. The DOMException is from the embed checking if it’s embedded on the Twitch website or somewhere else. The product 404 could technically be “fixed” by returning 200 and checking the contents of the response body instead, but it’s better to use the real response codes IMO.