Publish to service endpoint without reply subject causes panic

[liamkinne]

Observed behavior

Publishing to a subject used by a service endpoint causes the service to panic when running .respond().
See: https://github.com/nats-io/nats.rs/blob/4417346a772c365fe8f7b31d595c61dce190a007/async-nats/src/service/mod.rs#L757C9-L757C57

Expected behavior

The respond call should return an error to be handled by the caller.

Server and client version

NATS server 2.10
async-nats 0.45.0

Host environment

N/A

Steps to reproduce

1. Run any example service that calls .respond()
2. Publish without a reply subject specified: nats pub test ""

[vkolomeyko]

I wonder if this is an issue.
Calling .respond() without providing reply subject might not make too much sense. Hence the method corectly panics early on.

The respond call should return an error to be handled by the caller.

@liamkinne
Would you rather have something like:

        let reply = match self.message.reply.clone() {
            None => { return Err(PublishError::with_source(BadSubject, "Missing reply subject"))}
            Some(subject) => subject
        };

?

[liamkinne]

You are right that it's user error to try respond without a reply subject. It just sucks to have the program panic instead of having an Err returned.

Yes I am happy with that. I will open a PR.

[Jarema]

It's an error to send a pub without a reply subject, but it definitely should not panic.
@liamkinne - would be great if you could open a PR!