Add error handling to json_consumer_example.go (confluentinc#1234)

Add error handling for SubscribeTopics call

Co-authored-by: Robert Yokota <[email protected]>

Author: CaelRowley

examples/json_consumer_example/json_consumer_example.go

@@ -76,6 +76,11 @@ func main() {
 
 	err = c.SubscribeTopics(topics, nil)
 
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to subscribe to topics: %s\n", err)
+		os.Exit(1)
+	}
+
 	run := true
 
 	for run {