libweave: Fixed error message

auth_code is optional and can be empty.

BUG=none
TEST=none

Change-Id: Ic20598bd6e48cf3b1fbf31ac2af03c7cce908167
Reviewed-on: https://chromium-review.googlesource.com/289694
Reviewed-by: Vitaly Buka <vitalybuka@chromium.org>
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Vitaly Buka <vitalybuka@chromium.org>
Tested-by: Vitaly Buka <vitalybuka@chromium.org>

libweave/src/privet/privet_handler.cc

diff --git a/libweave/src/privet/privet_handler.cc b/libweave/src/privet/privet_handler.cc
index 914922e..7fee03b 100644
--- a/libweave/src/privet/privet_handler.cc
+++ b/libweave/src/privet/privet_handler.cc
@@ -646,10 +646,10 @@
   }
 
   if (requested_auth_scope > max_auth_scope) {
-    chromeos::Error::AddToPrintf(
-        &error, FROM_HERE, errors::kDomain, errors::kAccessDenied,
-        "Scope '%s' is not allowed for '%s'",
-        EnumToString(requested_auth_scope).c_str(), auth_code.c_str());
+    chromeos::Error::AddToPrintf(&error, FROM_HERE, errors::kDomain,
+                                 errors::kAccessDenied,
+                                 "Scope '%s' is not allowed",
+                                 EnumToString(requested_auth_scope).c_str());
     return ReturnError(*error, callback);
   }