Add error handling for SubscribeTopics function call

This commit adds error handling to the main function in consumer_example.go file. Specifically, it checks for errors returned by the SubscribeTopics function call and exits the program with an error message if the subscription fails. This ensures robustness and graceful handling of errors during topic subscription.

examples/consumer_example/consumer_example.go

@@ -70,6 +70,11 @@ func main() {
 
 	err = c.SubscribeTopics(topics, nil)
 
+	if err != nil {
+        	fmt.Fprintf(os.Stderr, "Failed to subscribe to topics: %v\n", err)
+        	os.Exit(1)
+        }
+
 	run := true
 
 	for run {