Fix Fatal error on templates management (joomla#45198)

Thanks @joomdonation and testers for speedy turnaround!

Author: joomdonation

administrator/components/com_templates/tmpl/template/default_description.php

@@ -27,5 +27,5 @@
     <h2><?php echo ucfirst($this->template->element); ?></h2>
     <?php $client = ApplicationHelper::getClientInfo($this->template->client_id); ?>
     <p><?php $this->template->xmldata = TemplatesHelper::parseXMLTemplateFile($client->path, $this->template->element); ?></p>
-    <p><?php echo Text::_($this->template->xmldata->get('description')); ?></p>
+    <p><?php echo Text::_($this->template->xmldata->description); ?></p>
 </div>

administrator/components/com_templates/tmpl/templates/default.php

@@ -98,21 +98,21 @@
                                     <?php endif; ?>
                                 </th>
                                 <td class="small d-none d-md-table-cell text-center">
-                                    <?php echo $this->escape($item->xmldata->get('version')); ?>
+                                    <?php echo $this->escape($item->xmldata->version); ?>
                                 </td>
                                 <td class="small d-none d-md-table-cell text-center">
-                                    <?php echo $this->escape($item->xmldata->get('creationDate')); ?>
+                                    <?php echo $this->escape($item->xmldata->creationDate); ?>
                                 </td>
                                 <td class="d-none d-md-table-cell text-center">
-                                    <?php if ($author = $item->xmldata->get('author')) : ?>
+                                    <?php if ($author = $item->xmldata->author) : ?>
                                         <div><?php echo $this->escape($author); ?></div>
                                     <?php else : ?>
                                         &mdash;
                                     <?php endif; ?>
-                                    <?php if ($email = $item->xmldata->get('authorEmail')) : ?>
+                                    <?php if ($email = $item->xmldata->authorEmail) : ?>
                                         <div><?php echo $this->escape($email); ?></div>
                                     <?php endif; ?>
-                                    <?php if ($url = $item->xmldata->get('authorUrl')) : ?>
+                                    <?php if ($url = $item->xmldata->authorUrl) : ?>
                                         <div><a href="<?php echo $this->escape($url); ?>"><?php echo $this->escape($url); ?></a></div>
                                     <?php endif; ?>
                                 </td>