[Bug] Producer blocks on Send when Schema fails to Encode

[samuelhewitt]

Expected behavior

When calling producer.Send() and producer.SendAsync(), the relevant error should be returned when the ProducerMessage.Value cannot be encoded by the schema. The publish Semaphore should also be released.

Actual behavior

Send never returns and SendAsync never executes the callback. Additionally, the publish Semaphore is never released.

Steps to reproduce

Execute code similar to the following, observe that Send never returns.

	// create producer
	producer, err := client.CreateProducer(ProducerOptions{
		Topic:  topic,
		Schema: NewAvroSchema("{\"type\":\"string\"}", nil),
	})
	defer producer.Close()

	// producer should send return an error as message is Int64, but schema is String
	mid, err := producer.Send(ctx, &ProducerMessage{
		Value: int64(1),
	})

System configuration

Pulsar client version: v0.8.0
Pulsar version: 2.10.0