Fixes some potential memory leaks in unit tests, cleanup

PkmnLibRSharp/PkmnLibRSharp.csproj

@@ -7,6 +7,12 @@
         <Nullable>enable</Nullable>
     </PropertyGroup>
 
+    <PropertyGroup Condition=" '$(Configuration)' == 'Debug' ">
+      <WarningLevel>6</WarningLevel>
+      <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+      <WarningsAsErrors>;NU1605;CA2000</WarningsAsErrors>
+    </PropertyGroup>
+
     <ItemGroup>
       <None Update="libpkmn_lib.so">
         <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>

PkmnLibRSharp/Utils/ExternPointer.cs

@@ -49,8 +49,8 @@ namespace PkmnLibSharp.Utils
                 return _ptr;
             }
         }
-        
-        internal IntPtr TakeOwnership()
+
+        private IntPtr TakeOwnership()
         {
             if (!_isOwner)
             {
@@ -67,17 +67,12 @@ namespace PkmnLibSharp.Utils
             return ptr;
         }
 
-        internal void Invalidate()
+        private void Invalidate()
         {
             _isInvalidated = true;
             CacheHandler.RemoveCache(_ptr);
         }
         
-        ~ExternPointer()
-        {
-            Dispose();
-        }
-
         public void Dispose()
         {
             if (_isDisposed)