add: err_list_push();
context: void io_flush(void){	int fd = multiplex_out_fd;	if (!io_buffer_count || no_flush) return;	if (io_multiplexing_out) {		mplex_write(fd, FNONE, io_buffer, io_buffer_count);	} else {		writefd_unbuffered(fd, io_buffer, io_buffer_count);	}	io_buffer_count = 0;}