fix iterator_get_next for dataset.

src/TensorFlowNET.Core/Binding.Util.cs

@@ -270,12 +270,10 @@ namespace Tensorflow
             int i = 0;
             foreach(var val in values)
             {
-                if (i < start)
-                {
-                    i++;
+                if (i++ < start)
                     continue;
-                }
-                yield return (i, val);
+                
+                yield return (i - start, val);
             }
         }
 

src/TensorFlowNET.Core/Data/DatasetV2.cs

@@ -78,9 +78,19 @@ namespace Tensorflow
         {
             var ownedIterator = new OwnedIterator(this);
 
-            Tensor[] results = ownedIterator.next();
-            while (results != null)
+            bool stop = false;
+            Tensor[] results = null;
+            while (!stop)
             {
+                try
+                {
+                    results = ownedIterator.next();
+                }
+                catch (StopIteration)
+                {
+                    stop = true;
+                }
+
                 yield return (results[0], results[1]);
             }
         }

src/TensorFlowNET.Core/Data/OwnedIterator.cs

@@ -35,6 +35,15 @@ namespace Tensorflow
         }
 
         public Tensor[] next()
-            => ops.iterator_get_next(_iterator_resource, _dataset.output_types, _dataset.output_shapes);
+        {
+            try
+            {
+                return ops.iterator_get_next(_iterator_resource, _dataset.output_types, _dataset.output_shapes);
+            }
+            catch (OutOfRangeError ex)
+            {
+                throw new StopIteration(ex.Message);
+            }
+        }
     }
 }

src/TensorFlowNET.Core/Exceptions/OutOfRangeError.cs

@@ -0,0 +1,17 @@
+using System;
+
+namespace Tensorflow
+{
+    public class OutOfRangeError : TensorflowException
+    {
+        public OutOfRangeError() : base()
+        {
+
+        }
+
+        public OutOfRangeError(string message) : base(message)
+        {
+
+        }
+    }
+}

src/TensorFlowNET.Core/Status/Status.cs

@@ -78,9 +78,18 @@ namespace Tensorflow
             if (Code != TF_Code.TF_OK)
             {
                 var message = Message;
-                Console.WriteLine(message);
+
                 if (throwException)
-                    throw new TensorflowException(message);
+                {
+                    switch (Code)
+                    {
+                        case TF_Code.TF_OUT_OF_RANGE:
+                            throw new OutOfRangeError(message);
+                        default:
+                            Console.WriteLine(message);
+                            throw new TensorflowException(message);
+                    }
+                }
             }
         }
 

src/TensorFlowNET.Core/Tensors/Tensor.Implicit.cs

@@ -3,6 +3,7 @@ using System;
 using System.Collections.Generic;
 using System.Text;
 using Tensorflow.Eager;
+using static Tensorflow.Binding;
 
 namespace Tensorflow
 {
@@ -21,5 +22,8 @@ namespace Tensorflow
 
         public static implicit operator Tensor(IntPtr handle)
             => new Tensor(handle);
+
+        public static implicit operator Tensor(NDArray nd)
+            => tf.convert_to_tensor(nd);
     }
 }