When the topic is deleted, call consumer.Close() program panic

1. client.Subscribe create consumer
2. delete the topic on the console
3. consumer call Close() close the consumer and panic

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0xe9fab4]

goroutine 54085 [running]:
mq-proxy/vendor/github.com/apache/pulsar-client-go/pulsar.(*partitionConsumer).getConsumerState(...)
/var/jenkins_home/workspace/cci-905269-131348/ci-workspace/src/mq-proxy/vendor/github.com/apache/pulsar-client-go/pulsar/consumer_partition.go:466
mq-proxy/vendor/github.com/apache/pulsar-client-go/pulsar.(*partitionConsumer).Close(...)
/var/jenkins_home/workspace/cci-905269-131348/ci-workspace/src/mq-proxy/vendor/github.com/apache/pulsar-client-go/pulsar/consumer_partition.go:475
cmq-proxy/vendor/github.com/apache/pulsar-client-go/pulsar.(*consumer).Close.func1.1(0xc000377260)
/var/jenkins_home/workspace/cci-905269-131348/ci-workspace/src/mq-proxy/vendor/github.com/apache/pulsar-client-go/pulsar/consumer_impl.go:568 +0x54
created by mq-proxy/vendor/github.com/apache/pulsar-client-go/pulsar.(*consumer).Close.func1
/var/jenkins_home/workspace/cci-905269-131348/ci-workspace/src/mq-proxy/vendor/github.com/apache/pulsar-client-go/pulsar/consumer_impl.go:566 +0xb9

This is unreasonable. For example, the administrator deletes a user, the user loginout, causing the system to crash