A return value typo error of print_trading_env() function (livr -> live) is modified.
inherits(orders, "data.frame") condition is added to kis_cancel_all() function, because the get_orders() function inside of kis_cancel_all() function returns a list of error code if the class of return value is not a data.frame. So if get_orders() function returns a list of error code, the print_trading_env() function returns the same list of error code.