NDArray.FromMultiDimArray<T>: Added guards.

Author: Nucs

src/NumSharp.Core/Casting/NdArrayFromMultiDimArr.cs

@@ -26,10 +26,18 @@ public partial class NDArray
         ///     Creates an NDArray out of given array of type <typeparamref name="T"/>
         /// </summary>
         /// <param name="ndarray"></param>
+        /// <param name="copy">true for making </param>
         public static NDArray FromMultiDimArray<T>(Array ndarray, bool copy = true) where T : unmanaged
         {
-            if (ndarray.GetType().GetElementType().IsArray)
-                throw new Exception("Given array is a jagged array.");
+            if (ndarray == null)
+                throw new ArgumentNullException(nameof(ndarray));
+
+            var elem = ndarray.GetType().GetElementType();
+            if (elem == null || elem.IsArray)
+                throw new ArgumentException("Given array is not a multi-dimensional array (e.g. T[,,]).");
+
+            if (elem != typeof(T))
+                throw new ArgumentException("T constraint must match the element type of the given array.");
 
             switch (ndarray.Rank)
             {
@@ -67,7 +75,7 @@ public static NDArray FromMultiDimArray<T>(Array ndarray, bool copy = true) wher
                     return np.array((T[,,,,,,,,,,,,,,,])ndarray, copy);
             }
 
-            throw new NotImplementedException("FromMultiDimArray<T>(Array dotNetArray)");
+            throw new NotSupportedException();
         }
     }
 }