Server sent events not working

Hi all,

I am developing a Jira cloud app which listens on webhook events for issues. In case an issue is created / updated I am catching the issue changelog and doing a conversion routine on my server side.
In case the server was not able to convert the data, I want the client know about this and emit an event to an error endpoint /events/errors.

On client-side (so far pure JS) I want to work with a so called Server Sent Event (SSE) (Server Sent Events) which listens on that endpoint and shall throw an error flag whenver an event was emitted. Somehow, Firefox is not working with SSE.

Does someone know, if SSE is generally forbidden to use in terms of extension development? and does someone know about another (valid) lightweight solution which solves my problem?

Best Valentin