The workerClientErrorFrom() was returning an `*clienterrors.Error` and
an `error` (if something with the conversation goes wrong.
But the calling code was expecting that even if an `error` is returned
the `*clienterrors.Error` is still valid. The caller would then just
log the error. As returning a valid `value` even when there is an
`error` is an unexpected pattern this commit changes the code to
always return a `*clienterrors.Error` and log any issue via the
logger.
