[BUGFIX] Initialize properties

html/typo3conf/ext/t3omy/Classes/Domain/Model/MyProfile.php

 <?php
 declare(strict_types=1);
+
 namespace T3o\T3omy\Domain\Model;
 
 use TYPO3\CMS\Extbase\Domain\Model\FrontendUser;
@@ -13,18 +14,17 @@ class MyProfile extends FrontendUser
     /**
      * @var string
      */
-    public $github;
+    public $github = '';
 
     /**
      * @var string
      */
-    public $twitter;
+    public $twitter = '';
 
     /**
      * @var string
      */
-    public $facebook;
-
+    public $facebook = '';
 
 
     /**