Add an error message for udns error DNS_E_NODATA

In cases where the DNS server does not respond “domain not found” but
“domain found, but no IP for that record type”, we just say “domain not
found” too (instead of nothing, previously).

src/network/resolver.cpp

@@ -21,6 +21,7 @@ static std::map<int, std::string> dns_error_messages {
     {DNS_E_TEMPFAIL, "Timeout while contacting DNS servers"},
     {DNS_E_PROTOCOL, "Misformatted DNS reply"},
     {DNS_E_NXDOMAIN, "Domain name not found"},
+    {DNS_E_NODATA, "Domain name not found"},
     {DNS_E_NOMEM, "Out of memory"},
     {DNS_E_BADQUERY, "Misformatted domain name"}
 };