Throw exception if pointer in PointerWrapper is accessed after dispose

PkmnLibSharp/PointerWrapper.cs

@@ -5,7 +5,19 @@ namespace PkmnLibSharp
 {
     public abstract class PointerWrapper : IDisposable
     {
-        internal readonly IntPtr Ptr;
+        private readonly IntPtr _ptr;
+        internal IntPtr Ptr
+        {
+            get
+            {
+                if (_isDeleted)
+                {
+                    throw new Exception("Pointer access after dispose detected. This is not legal, and will cause native exceptions.");
+                }
+                return _ptr;
+            }
+        }
+
         private bool _isDeleted = false;
 
         private static readonly ConcurrentDictionary<IntPtr, WeakReference<object>> Cached =
@@ -13,7 +25,7 @@ namespace PkmnLibSharp
 
         protected PointerWrapper(IntPtr ptr)
         {
-            Ptr = ptr;
+            _ptr = ptr;
             var weakRef = new WeakReference<object>(this);
             Cached.TryAdd(ptr, weakRef);
         }