Fix issue with editing an old registrant and form fields being hidden

modules/recurring_events_registration/src/Form/RegistrantForm.php

@@ -301,6 +301,10 @@ class RegistrantForm extends ContentEntityForm {
    *   The form state interface.
    */
   protected function hideFormFields(array &$form, FormStateInterface $form_state) {
+    /* @var $entity \Drupal\recurring_events_registration\Entity\Registrant */
+    $entity = $this->entity;
+    $new = $entity->isNew();
+
     $form_fields = $this->fieldManager->getFieldDefinitions('registrant', $this->entity->getBundle());
 
     $availability = $this->creationService->retrieveAvailability();
@@ -311,7 +315,7 @@ class RegistrantForm extends ContentEntityForm {
     // no spaces left, and no waitlist.
     if (($availability === 0 && !$waitlist) || !$registration_open) {
       foreach ($form_fields as $field_name => $field) {
-        if (isset($form[$field_name])) {
+        if (isset($form[$field_name]) && $new) {
           $form[$field_name]['#printed'] = TRUE;
         }
       }