core: don't check error parameter of get_name_owner_handler()

It's a *return* parameter, not an input parameter. Yes, this is a bit
confusing for method call replies, but we try to use the same message
handler for all incoming messages, hence the parameter. We are supposed
to write any error into it we encounter, if we want, and our caller will
log it, but that's it.

src/core/unit.c

@@ -3218,11 +3218,6 @@ static int get_name_owner_handler(sd_bus_message *message, void *userdata, sd_bu
 
         u->get_name_owner_slot = sd_bus_slot_unref(u->get_name_owner_slot);
 
-        if (sd_bus_error_is_set(error)) {
-                log_error("Failed to get name owner from bus: %s", error->message);
-                return 0;
-        }
-
         e = sd_bus_message_get_error(message);
         if (sd_bus_error_has_name(e, "org.freedesktop.DBus.Error.NameHasNoOwner"))
                 return 0;