Unfortunately detecting client disconnects isn't particularly easy with SSE, given that it's a one-way communication channel (unlike WebSockets which are two-way).
Even just talking about disconnects, there are several different types of disconnect that can happen such as: 1. The `EventSource.close()` method is called in the JS side, closing the connection from the client: <https://developer.mozilla.org/en-US/docs/Web/API/EventSource/close> 2. The user closes the web browser/tab or navigates away 3. The user loses network connection (e.g. loses 4G signal or WiFi signal, or unplugs their network cable) All of these will behave in slightly different ways, and detecting them isn't particularly easy in some cases depending on keep-alives and such. You can probably catch an exception from the underlying `asyncdispatch.send()` call which actually transmits data to the client to catch most cases where the client disconnects though.
