apply Error Data packet in challenge status

Change-Id: I629e57ad96d33ad77dcc939a25577a15afcf2886
diff --git a/src/protocol-detail/error.hpp b/src/protocol-detail/error.hpp
index c03ec05..1234233 100644
--- a/src/protocol-detail/error.hpp
+++ b/src/protocol-detail/error.hpp
@@ -27,18 +27,18 @@
 namespace ndn {
 namespace ndncert {
 
-class ERROR {
+class ErrorTLV {
 public:
   /**
    * Encode error information into a Data content TLV
    */
   static Block
-  encodeDataContent(Error errorCode, const std::string& description);
+  encodeDataContent(ErrorCode errorCode, const std::string& description);
 
   /**
    * Decode error information from Data content TLV
    */
-  static std::tuple<Error, std::string>
+  static std::tuple<ErrorCode, std::string>
   decodefromDataContent(const Block& block);
 };