time: Fix bug in ndn_toIsoString: Return an error if the time is out of range.
diff --git a/ndn-cpp/c/errors.c b/ndn-cpp/c/errors.c
index a77a858..20f69ef 100644
--- a/ndn-cpp/c/errors.c
+++ b/ndn-cpp/c/errors.c
@@ -77,6 +77,8 @@
     return      "Name component does not begin with the expected marker";
   case NDN_ERROR_Time_functions_are_not_supported_by_the_standard_library:
     return      "Time functions are not supported by the standard library";
+  case NDN_ERROR_Calendar_time_value_out_of_range:
+    return      "Calendar time value out of range";
   default:
     return "unrecognized ndn_Error code";  
   }