Unable to get MqttClientPublishResult from PublishAsync without error thrown?

[invisicow]

Discussed in #2139

^{Originally posted by invisicow January 17, 2025}
Hi,

I am testing my error handling when calling PublishAsync() to a bad topic, such as "####", but I am getting unexpected behavior.

Expected:
I expected PublishAsync() to return an MqttClientPublishResult instance with ReasonCode having value MqttClientPublishReasonCode.TopicNameInvalid.

Actual:
Instead, I am getting exception

MQTTnet.Exceptions.MqttProtocolViolationException: 'The character '#' is not allowed in topics.'

This is rather unfortunate, because using specific MqttClientPublishReasonCode values from the MqttClientPublishResult would help my error handling. Is there a way to receive this result object back without the method throwing an error?

Thank you.