fix(core): Handles a rare NPE with LoginTimer (#508)

Projects/UOContent/Items/Books/BookPackets.cs

@@ -13,7 +13,6 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>. *
  *************************************************************************/
 
-using System;
 using System.Buffers;
 using System.IO;
 using Server.Network;

Projects/UOContent/Items/Misc/Corpses/Corpse.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Runtime.CompilerServices;
 using Server.ContextMenus;
 using Server.Engines.PartySystem;
 using Server.Engines.Quests.Doom;

Projects/UOContent/Items/Weapons/Abilities/FrenziedWhirlwind.cs

@@ -1,7 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
-using Server.Mobiles;
 using Server.Spells;
 
 namespace Server.Items