[SMALL FIX] Return null if catch EOFException

Return null if catch EOFException, just like function "asKeyValueIterator" in this class

Author: Mingfei <mingfei.shi@intel.com>

Closes #6703 from shimingfei/returnNull and squashes the following commits:

205deec [Mingfei] return null if catch EOFException

1 files changed, 1 insertions, 0 deletions

diff --git a/core/src/main/scala/org/apache/spark/serializer/Serializer.scala b/core/src/main/scala/org/apache/spark/serializer/Serializer.scala
index f1bdff96d3..bd2704dc81 100644
--- a/core/src/main/scala/org/apache/spark/serializer/Serializer.scala
+++ b/core/src/main/scala/org/apache/spark/serializer/Serializer.scala
@@ -182,6 +182,7 @@ abstract class DeserializationStream {
       } catch {
         case eof: EOFException =>
           finished = true
+          null
       }
     }