EDNS: Fixed adding OPT to packet.

src/knot/nameserver/internet.c

@@ -655,9 +655,12 @@ static int solve_additional(int state, knot_pkt_t *pkt,
                             struct query_data *qdata, void *ctx)
 {
 	/* Put OPT RR. */
-	int ret = knot_pkt_put(pkt, COMPR_HINT_NONE, pkt->opt_rr, 0);
-	if (ret != KNOT_EOK) {
-		return ERROR;
+	int ret;
+	if (pkt->opt_rr != NULL) {
+		ret = knot_pkt_put(pkt, COMPR_HINT_NONE, pkt->opt_rr, 0);
+		if (ret != KNOT_EOK) {
+			return ERROR;
+		}
 	}
 
 	/* Scan all RRs in ANSWER/AUTHORITY. */