Remove HasValue check

...since it does it implicitly already.

src/Discord.Net.Rest/Entities/Channels/ChannelHelper.cs

@@ -76,7 +76,7 @@ namespace Discord.Rest
         public static async Task<RestInviteMetadata> CreateInviteAsync(IGuildChannel channel, BaseDiscordClient client,
             int? maxAge, int? maxUses, bool isTemporary, bool isUnique, RequestOptions options)
         {
-            if (maxAge.HasValue && maxAge > 86400)
+            if (maxAge > 86400)
                 throw new ArgumentOutOfRangeException(nameof(maxAge), maxAge,
                     "The maximum age of an invite must be less than or equal to a day (86400).");
             var args = new API.Rest.CreateChannelInviteParams