int bt_error_append_cause_from_unknown(struct bt_error *error,
const char *module_name, const char *file_name,
uint64_t line_no, const char *msg_fmt, va_list args)
int bt_error_append_cause_from_unknown(struct bt_error *error,
const char *module_name, const char *file_name,
uint64_t line_no, const char *msg_fmt, va_list args)