Update web UX when server side error or hit stop + no task running

- Ack websocket interrupt even when no task running
  Otherwise chat UX isn't updated to indicate query has stopped
  processing for this edge case

- Mark chat request as not being procesed on server side error

src/interface/web/app/chat/page.tsx

@@ -359,6 +359,7 @@ export default function Chat() {
                     return;
                 } else if (controlMessage.error) {
                     console.error("WebSocket error:", controlMessage.error);
+                    setProcessQuerySignal(false);
                     return;
                 }
             } catch {