Method onError

tests/test_tcp.cpp:88–88

    void onConnected(std::shared_ptr<TCPSession>& session) override { connected = true; ++clients; }
    void onDisconnected(std::shared_ptr<TCPSession>& session) override { disconnected = true; --clients; }
    void onError(int error, const std::string& category, const std::string& message) override { errors = true; }

public:
    std::atomic<bool> started{false};