SQLSTATE for replication connection failures

So far as I can find, just about everyplace that deals with replication
connections has slipshod error reporting.  An example from worker.c is

        LogRepWorkerWalRcvConn = walrcv_connect(MySubscription->conninfo, true,
                                                MySubscription->name, &err);
        if (LogRepWorkerWalRcvConn == NULL)
            ereport(ERROR,
                    (errmsg("could not connect to the publisher: %s", err)));

Because of the lack of any errcode() call, this failure will be reported
as XX000 ERRCODE_INTERNAL_ERROR, which is surely not appropriate.
worker.c is in good company though, because EVERY caller of walrcv_connect
is equally slipshod.

Shall we just use ERRCODE_CONNECTION_FAILURE for these failures, or
would it be better to invent another SQLSTATE code?  Arguably,
ERRCODE_CONNECTION_FAILURE is meant for failures of client connections;
but on the other hand, a replication connection is a sort of client.

            regards, tom lane