Fix an error message when calling "transaction.search" with a non-transactional object PHID as an "objectIdentifier"

Summary: See PHI1499. This error message doesn't provide parameters, and can be a little bit more helpful.

Test Plan: {F6957550}

Differential Revision: https://secure.phabricator.com/D20859

src/applications/transactions/conduit/TransactionSearchConduitAPIMethod.php

@@ -103,8 +103,11 @@ EOREMARKUP
     if (!($object instanceof PhabricatorApplicationTransactionInterface)) {
       throw new Exception(
         pht(
-          'Object "%s" does not implement "%s", so transactions can not '.
-          'be loaded for it.'));
+          'Object "%s" (of type "%s") does not implement "%s", so '.
+          'transactions can not be loaded for it.',
+          $object_name,
+          get_class($object),
+          'PhabricatorApplicationTransactionInterface'));
     }
 
     $xaction_query = PhabricatorApplicationTransactionQuery::newQueryForObject(