hardcoded decklink mode fix

libs/dmf-node/src/control_server.cpp

@@ -29,17 +29,18 @@ struct ControlServer::Impl {
     struct lws_context* context = nullptr;
 };
 
-static void dispatch_command(ControlServerData* data, const nlohmann::json& msg) {
+static nlohmann::json dispatch_command(ControlServerData* data, const nlohmann::json& msg) {
     if (!msg.contains("cmd")) {
         spdlog::warn("Control: message missing 'cmd' field");
-        return;
+        return {{"error", "missing 'cmd' field"}};
     }
     auto cmd = msg["cmd"].get<std::string>();
     auto it = data->commands.find(cmd);
     if (it != data->commands.end()) {
-        it->second(msg);
+        return it->second(msg);
     } else {
         spdlog::warn("Control: unknown command '{}'", cmd);
+        return {{"error", "unknown command: " + cmd}};
     }
 }
 
@@ -102,8 +103,8 @@ static int callback_all(struct lws* wsi, enum lws_callback_reasons reason,
         }
         try {
             auto msg = nlohmann::json::parse(ps->http_body);
-            dispatch_command(ps->data, msg);
-            return send_http_json(wsi, "200 OK", R"({"ok":true})");
+            auto result = dispatch_command(ps->data, msg);
+            return send_http_json(wsi, "200 OK", result.dump());
         } catch (const nlohmann::json::parse_error& e) {
             return send_http_json(wsi, "400 Bad Request",
                                  nlohmann::json({{"error", e.what()}}).dump());