SImplify code and handle Core code

Author: fredericDelaporte

src/NHibernate/Collection/Generic/SetHelpers/SetSnapShot.cs

@@ -120,16 +120,10 @@ void ICollection.CopyTo(Array array, int index)
 				return;
 			}
 
-			if (array.GetType().GetElementType().IsAssignableFrom(typeof(T)))
-			{
-				if (_hasNull)
-					array.SetValue(default(T), index);
-				ICollection keysCollection = _values.Keys;
-				keysCollection.CopyTo(array, index + (_hasNull ? 1 : 0));
-				return;
-			}
-
-			throw new ArgumentException($"Array must be of type {typeof(T[])}.", nameof(array));
+			if (_hasNull)
+				array.SetValue(default(T), index);
+			ICollection keysCollection = _values.Keys;
+			keysCollection.CopyTo(array, index + (_hasNull ? 1 : 0));
 		}
 
 		public int Count => _values.Count + (_hasNull ? 1 : 0);
@@ -163,12 +157,14 @@ protected SetSnapShot(SerializationInfo info, StreamingContext context) : base(i
 
 		void ICollection.CopyTo(Array array, int index)
 		{
-			if (!(array is T[] typedArray))
+			if (array is T[] typedArray)
 			{
-				throw new ArgumentException($"Array must be of type {typeof(T[])}.", nameof(array));
+				CopyTo(typedArray, index);
+				return;
 			}
 
-			CopyTo(typedArray, index);
+			ICollection collection = this;
+			collection.CopyTo(array, index);
 		}
 
 		bool ICollection.IsSynchronized => false;