mgmt: Fixing regression introduced by change in the library

After more consistent usage of exceptions (most of the exceptions now
derived from Tlv::Error), `ndn::io::load` would not normally throw an
exception.

Change-Id: Ifd32653e681b94829007db3750e04754e9976fbd
diff --git a/daemon/mgmt/command-validator.cpp b/daemon/mgmt/command-validator.cpp
index ac08228..ad3443c 100644
--- a/daemon/mgmt/command-validator.cpp
+++ b/daemon/mgmt/command-validator.cpp
@@ -119,15 +119,19 @@
         }
       catch(const std::runtime_error& error)
         {
-          std::string msg = "Malformed certificate file " + certfilePath.native();
-          if (!isDryRun)
-            {
-              throw ConfigFile::Error(msg);
-            }
-          aggregateErrors(dryRunErrors, msg);
-          continue;
+          // do nothing
         }
 
+      if (!static_cast<bool>(id)) {
+        std::string msg = "Malformed certificate file " + certfilePath.native();
+        if (!isDryRun)
+          {
+            throw ConfigFile::Error(msg);
+          }
+        aggregateErrors(dryRunErrors, msg);
+        continue;
+      }
+
       in.close();
 
       const ConfigSection* privileges = 0;