ResolveMdnsName returns empty array instead of null when mDNS lookup …

…fails. (#1119)

src/net/ICE/RtpIceChannel.cs

@@ -2652,7 +2652,7 @@ private async Task<IPAddress[]> ResolveMdnsName(RTCIceCandidate candidate)
             if (MdnsResolve != null)
             {
                 var address = await MdnsResolve(candidate.address).ConfigureAwait(false);
-                return address != null ? new IPAddress[] { address } : null;
+                return address != null ? new IPAddress[] { address } : Array.Empty<IPAddress>();
             }