Switch connection exception logging to debug

This change avoids the log spam resulting from the client
closing ConfigService connections uncleanly.

EchoRelay.Core/Server/Services/Service.cs

@@ -188,7 +188,7 @@ internal async Task HandleConnection(HttpListenerContext context, WebSocket webS
                 try {
                 await webSocket.CloseAsync(WebSocketCloseStatus.InternalServerError, "", CancellationToken.None);
                 } catch {}
-                Log.Warning("An exception occurred while handling a websocket connection: {0}", e);
+                Log.Debug("An exception occurred while handling a websocket connection: {0}", e);
             }
             finally
             {