resolved: properly propagate query candidate error

We already properly propagate errors from transactions to queries. Make sure that errors that happened during handling
of query candidates are propagated to the query, too.

src/resolve/resolved-dns-query.c

@@ -760,6 +760,15 @@ static void dns_query_accept(DnsQuery *q, DnsQueryCandidate *c) {
                 return;
         }
 
+        if (c->error_code != 0) {
+                /* If the candidate had an error condition of its own, start with that. */
+                state = DNS_TRANSACTION_ERRNO;
+                q->answer = dns_answer_unref(q->answer);
+                q->answer_rcode = 0;
+                q->answer_dnssec_result = _DNSSEC_RESULT_INVALID;
+                q->answer_errno = c->error_code;
+        }
+
         SET_FOREACH(t, c->transactions, i) {
 
                 switch (t->state) {