diff --git a/Classes/Controller/Form.php b/Classes/Controller/Form.php
index 71db5427..b0dfda0e 100644
--- a/Classes/Controller/Form.php
+++ b/Classes/Controller/Form.php
@@ -36,7 +36,7 @@ class Form extends AbstractController
      *
      * @var array
      */
-    protected $errors;
+    protected $errors = [];
 
     /**
      * Holds the prefix value of all parameters of this form.
diff --git a/Classes/Finisher/Mail.php b/Classes/Finisher/Mail.php
index 250e19f4..6c6109e6 100644
--- a/Classes/Finisher/Mail.php
+++ b/Classes/Finisher/Mail.php
@@ -3,6 +3,7 @@
 namespace Typoheads\Formhandler\Finisher;
 
 use TYPO3\CMS\Core\Utility\GeneralUtility;
+use Typoheads\Formhandler\Mailer\MailerInterface;
 
 /*                                                                        *
  * This script is part of the TYPO3 project - inspiring people to share!  *
@@ -68,6 +69,8 @@
  */
 class Mail extends AbstractFinisher
 {
+    protected MailerInterface $emailObj;
+    protected ?string $predefined = null;
     /**
      * The main method called by the controller
      *
diff --git a/Classes/Interceptor/AbstractInterceptor.php b/Classes/Interceptor/AbstractInterceptor.php
index 4d0a3978..d153f7d3 100644
--- a/Classes/Interceptor/AbstractInterceptor.php
+++ b/Classes/Interceptor/AbstractInterceptor.php
@@ -22,6 +22,9 @@
  */
 abstract class AbstractInterceptor extends AbstractComponent
 {
+    protected array $doNotSanitizeFields = [];
+    protected array $removeChars = [];
+
     /**
      * Logs an action of an interceptor, e.g. if Interceptor_IPBlocking blocked a request.
      *
diff --git a/Classes/Session/AbstractSession.php b/Classes/Session/AbstractSession.php
index 10308a83..17df8be3 100644
--- a/Classes/Session/AbstractSession.php
+++ b/Classes/Session/AbstractSession.php
@@ -28,6 +28,8 @@ abstract class AbstractSession extends AbstractClass
      */
     protected $started = false;
 
+    protected array $gp = [];
+
     /**
      * Starts a new session
      */
diff --git a/Classes/View/AbstractView.php b/Classes/View/AbstractView.php
index 73235d2d..b4bb2df3 100644
--- a/Classes/View/AbstractView.php
+++ b/Classes/View/AbstractView.php
@@ -42,6 +42,9 @@ abstract class AbstractView extends AbstractPlugin
      */
     public $extKey = 'formhandler';
 
+    protected array $settings = [];
+    protected array $errors = [];
+
     protected ?ContentObjectRenderer $cObj = null;
 
     /**
@@ -60,6 +63,7 @@ abstract class AbstractView extends AbstractPlugin
     protected Configuration $configuration;
     protected Globals $globals;
     protected GeneralUtility $utilityFuncs;
+    protected ?string $predefined = null;
 
     /**
      * The model of the view
diff --git a/Classes/View/Form.php b/Classes/View/Form.php
index 0f0a5699..f0368353 100644
--- a/Classes/View/Form.php
+++ b/Classes/View/Form.php
@@ -32,6 +32,8 @@ class Form extends AbstractView
      */
     protected $disableEncodingFields;
 
+    protected ?array $masterTemplates = null;
+
     /**
      * Main method called by the controller.
      *
@@ -64,7 +66,7 @@ public function render($gp, $errors)
         }
 
         //read master template
-        if (!isset($this->masterTemplates)) {
+        if ($this->masterTemplates === null) {
             $this->readMasterTemplates();
         }