Idiomatic way of passing error to consumer in a RPC-like client

[mellow loom]

It should be returned from read as the last argument in a multivalue return if needed

This is the idiom and convention.

We treat errors as values to avoid the unscalable abomination that is try-catch.

This does mean the caller has to handle errors on the way back up.

This is also normal

But it takes getting used to.

After coding in Java/C++ for years, I can't imagine going back.