Why librdkafka doesn't throw any error/exception even when wrong broker hostnames are passed?

Question

I am writing python app that used confluent_kafka api (which internally uses librdkafka) to calculate kafka throughput,however in this process i observed that even when I pass dummy broker name then application doesn't throw any error so am is missing soemthing or this is bug in api. Also what could be the better way of handling this?

import confluent_kafka
import json
import argparse
import time

def cmd_line_parse():
    parser = argparse.ArgumentParser("Arg Parser")
    parser.add_argument('-j','--json_config',help='command line argument for kafka configuration',required=True)
    parser.add_argument('-t','--topic_name',help='kafka topic name',required=True)
    parser.add_argument('-c','--msg_count',help='messages that you want to send to kafka topic for calculating throughput',default=500000,required=False)
    parser.add_argument('-s','--msg_size',help='message size(in bytes) against which you want to test',default=1024,required=False)
    args = parser.parse_args()
    return args

def print_throughput_stats(time_taken,msg_count,msg_size):
    print("Processed {0} messsages in {1:.2f} seconds".format(msg_count, time_taken))
    print("Throughput: {0:.2f} MB/s".format((msg_size*msg_count)/time_taken/(1024*1024)))

def main():
    args = cmd_line_parse()
    kafka_config_dict = json.loads(args.json_config)
    kafka_topic_name = args.topic_name
    producer = confluent_kafka.Producer(**kafka_config_dict)
    msg_payload = 'K'*args.msg_size
    start_time = time.time()
    for i in xrange(args.msg_count):
        producer.produce(kafka_topic_name,value=msg_payload)
    producer.poll(0)
    producer.flush()
    end_time = time.time()
    print_throughput_stats(end_time-start_time,args.msg_count,args.msg_size)

if __name__ == "__main__":
    try:
        main()
    except Exception as e:
        print("Exception Occured: {}".format(str(e)))

When I tested this application by passing incorrect broker there was no error/exception :

python check_throughput.py -t perf_test -j '{"bootstrap.servers":"dummy.com"}'