Fixes issue where getting battle from a pokemon could result in battle being in a deleted state.

PkmnLibSharp/Battling/Pokemon.cs

@@ -145,7 +145,7 @@ namespace PkmnLibSharp.Battling
             get
             {
                 var ptr = Creaturelib.Generated.Creature.GetBattle(Ptr);
-                if (_battle != null && _battle.Ptr == ptr) return _battle;
+                if (_battle != null && !_battle.IsDeleted && _battle.Ptr == ptr) return _battle;
                 if (TryResolvePointer(ptr, out _battle))
                     return _battle;
                 _battle = Constructor.Active.ConstructBattle(ptr);
@@ -157,7 +157,7 @@ namespace PkmnLibSharp.Battling
             get
             {
                 var ptr = Creaturelib.Generated.Creature.GetBattleSide(Ptr);
-                if (_battleSide != null && _battleSide.Ptr == ptr) return _battleSide;
+                if (_battleSide != null && !_battleSide.IsDeleted && _battleSide.Ptr == ptr) return _battleSide;
                 if (TryResolvePointer(ptr, out _battleSide))
                     return _battleSide;
                 _battleSide = new BattleSide(ptr);

PkmnLibSharp/Utilities/PointerWrapper.cs

@@ -21,7 +21,7 @@ namespace PkmnLibSharp.Utilities
             }
         }
 
-        protected bool IsDeleted { get; private set; } = false;
+        public bool IsDeleted { get; private set; } = false;
 
         private static readonly ConcurrentDictionary<IntPtr, WeakReference<PointerWrapper>> Cached =
             new ConcurrentDictionary<IntPtr, WeakReference<PointerWrapper>>();