[6.0] Fix fatal error private message (joomla#45213)

* Fix fatal error when view private message

* More change needed

* CS

Author: joomdonation

administrator/components/com_messages/src/Model/MessageModel.php

@@ -163,11 +163,12 @@ public function getItem($pk = null)
                             return false;
                         }
 
-                        $this->item->set('user_id_to', $message->user_id_from);
+                        $this->item->user_id_to = $message->user_id_from;
+
                         $re = Text::_('COM_MESSAGES_RE');
 
                         if (stripos($message->subject, $re) !== 0) {
-                            $this->item->set('subject', $re . ' ' . $message->subject);
+                            $this->item->subject = $re . ' ' . $message->subject;
                         }
                     }
                 } elseif ($this->item->user_id_to != $this->getCurrentUser()->id) {
@@ -188,7 +189,7 @@ public function getItem($pk = null)
 
             // Get the user name for an existing message.
             if ($this->item->user_id_from && $fromUser = new User($this->item->user_id_from)) {
-                $this->item->set('from_user_name', $fromUser->name);
+                $this->item->from_user_name = $fromUser->name;
             }
         }
 

administrator/components/com_messages/tmpl/message/default.php

@@ -33,7 +33,7 @@
     <div class="card-body">
         <dl class="mb-0">
             <dt><?php echo Text::_('COM_MESSAGES_FIELD_USER_ID_FROM_LABEL'); ?></dt>
-            <dd><?php echo $this->item->get('from_user_name'); ?></dd>
+            <dd><?php echo $this->item->from_user_name; ?></dd>
 
             <dt><?php echo Text::_('COM_MESSAGES_FIELD_DATE_TIME_LABEL'); ?></dt>
             <dd><?php echo HTMLHelper::_('date', $this->item->date_time, Text::_('DATE_FORMAT_LC2')); ?></dd>