It turns out that new candidate was there for a reason

Author: driusan

php/libraries/NDB_BVL_Instrument.class.inc

@@ -23,7 +23,7 @@ abstract class NDB_BVL_Instrument extends NDB_Page
     /**
      * The form object for this instrument.
      *
-     * @var    LorisForm
+     * @var    ?LorisForm
      * @access public
      */
     public $form;

test/unittests/NDB_BVL_Instrument_Test.php

@@ -1787,6 +1787,11 @@ function testToJsonParseSmartyDateTypeNotLorisForm()
             ],
             'NoResponse' => true
         ];
+
+        // Exercise the code intended to use QuickForm instead of
+        // LorisForm by making this->_instrument->form not a LorisForm.
+        $this->_instrument->form = null;
+
         $this->assertEquals($result, $this->_instrument->_toJSONParseSmarty($el));
     }