From 13b1b63b4edc513bb16588dc9875196efb5642f2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pavel=20S=CC=8Cavara?= <pavel.savara@cimpress.com>
Date: Fri, 8 May 2020 01:23:14 +0200
Subject: [PATCH] fix NullReferenceException on session run with
 ITensorOrOperation signature

---
 src/TensorFlowNET.Core/Sessions/BaseSession.cs |  3 ++-
 test/TensorFlowNET.UnitTest/SessionTest.cs     | 11 +++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/TensorFlowNET.Core/Sessions/BaseSession.cs b/src/TensorFlowNET.Core/Sessions/BaseSession.cs
index b25e77e5..5fcdc547 100644
--- a/src/TensorFlowNET.Core/Sessions/BaseSession.cs
+++ b/src/TensorFlowNET.Core/Sessions/BaseSession.cs
@@ -65,7 +65,8 @@ namespace Tensorflow
 
         public virtual NDArray run(ITensorOrOperation fetche, params FeedItem[] feed_dict)
         {
-            return _run(fetche, feed_dict)[0];
+            var results = _run(fetche, feed_dict);
+            return fetche is Tensor ? results[0] : null;
         }
 
         public virtual (NDArray, NDArray, NDArray, NDArray, NDArray) run(
diff --git a/test/TensorFlowNET.UnitTest/SessionTest.cs b/test/TensorFlowNET.UnitTest/SessionTest.cs
index ddb6fe5f..95d2d447 100644
--- a/test/TensorFlowNET.UnitTest/SessionTest.cs
+++ b/test/TensorFlowNET.UnitTest/SessionTest.cs
@@ -133,6 +133,17 @@ namespace TensorFlowNET.UnitTest
                 }
             }
         }
+        
+        [TestMethod]
+        public void Autocast_Case0()
+        {
+            var sess = tf.Session().as_default();
+            ITensorOrOperation operation = tf.global_variables_initializer();
+            // the cast to ITensorOrOperation is essential for the test of this method signature
+            var ret = sess.run(operation);
+
+            ret.Should().BeNull();
+        }        
 
         [TestMethod]
         public void Autocast_Case1()