Don't check and throw exception in a display function. We should check this at input side.

shadowsocks-csharp/Model/Server.cs

@@ -45,9 +45,7 @@ namespace Shadowsocks.Model
             string serverStr;
             // CheckHostName() won't do a real DNS lookup
             var hostType = Uri.CheckHostName( server );
-            if ( hostType == UriHostNameType.Unknown ) {
-                throw new FormatException("Invalid Server Address.");
-            }
+
             switch ( hostType ) {
                 case UriHostNameType.IPv6:
                     serverStr = $"[{server}]:{server_port}";