message: return empty string for no error
diff: @@ -14,7 +14,11 @@ namespace wampcc
  const char* uverr::message() const
  {
  + if (m_value == 0)
  + return "";
  + else {
  const char* s = uv_strerror(m_value); /* Can leak memory */
  return s ? s : "unknown";
  }
  }
  +}
  