fix ndarray to tensor implicit convertion.

src/TensorFlowNET.Core/Binding.Util.cs

@@ -508,6 +508,12 @@ namespace Tensorflow
 
         public static Shape GetShape(this object data)
         {
+            if (data is NDArray nd)
+                return nd.shape;
+
+            if (data is Tensor tensor)
+                return tensor.shape;
+
             if (!data.GetType().IsArray)
                 return Shape.Scalar;
 

src/TensorFlowNET.Core/NumPy/NDArray.Implicit.cs

@@ -37,7 +37,7 @@ namespace Tensorflow.NumPy
             => new NDArray(value);
 
         public static implicit operator Tensor(NDArray nd)
-            => nd._tensor;
+            => constant_op.constant(nd);
 
         public static implicit operator NDArray(Tensor tensor)
             => new NDArray(tensor);