Code cleanup

modules/ChatManagement/Handler/BanStickerSet.Utils.cs

@@ -34,7 +34,7 @@ public partial class BanStickerSet
 
     public async Task<bool> PreCommand(ParamParser.StickerSet.Param? stickerSetParam = null)
     {
-        if (stickerSetParam != null && !stickerSetParam.IsValid)
+        if (stickerSetParam is { IsValid: false })
         {
             await Reply("Неверный набор стикеров.");
             return false;

modules/ChatManagement/Handler/Greet.cs

@@ -1,5 +1,4 @@
-using System;
-using System.Linq;
+using System.Linq;
 using System.Threading.Tasks;
 using BotFramework;
 using BotFramework.Attributes;

modules/ChatManagement/Handler/Warn.cs

@@ -1,6 +1,4 @@
-#nullable enable
-
-using System.Threading.Tasks;
+using System.Threading.Tasks;
 using BotFramework.Attributes;
 using BotFramework.Enums;
 using Kruzya.TelegramBot.Core.Data;