Tweaked exception rethrow code.

src/NTwain/Internals/ExceptionExtensions.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
+using System.Runtime.ExceptionServices;
 using System.Text;
 using System.Threading.Tasks;
 
@@ -18,9 +19,13 @@ namespace NTwain.Internals
         {
             if (ex != null)
             {
+#if NET40
                 typeof(Exception).GetMethod("PrepForRemoting",
                     BindingFlags.NonPublic | BindingFlags.Instance)?.Invoke(ex, new object[0]);
                 throw ex;
+#else
+                ExceptionDispatchInfo.Capture(ex).Throw();
+#endif
             }
         }