diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index e9b4371..4bbb819 100755
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -16,7 +16,7 @@ Generally, the development philosophy is result orientated. This means that anyo
 
 Developers  are encouraged to pick open tasks with high priorities according to their own skill level. Senior developers may  directly assign tasks to developers based on their importance. New  developers may find it easier to start with a task that has a low  priority as they often also have a lower difficulty.
 
-Open tasks can be found in the project overview: [PROJECT.md](../Project/PROJECT.md)
+Open tasks can be found in the project overview: [PROJECT.md](https://github.com/Karaka-Management/Organization-Guide/blob/master/Project/PROJECT.md)
 
 Tasks  currently in development are prefixed in the priority column with an  asterisk `*` and a name tag in the task description of the developer who is working on the task.
 
diff --git a/Controller/ApiController.php b/Controller/ApiController.php
index c509636..8e2c85b 100755
--- a/Controller/ApiController.php
+++ b/Controller/ApiController.php
@@ -49,8 +49,8 @@ final class ApiController extends Controller
         $val = [];
         if (($val['title'] = empty($request->getData('title')))
             || ($val['color'] = (!empty($request->getData('color'))
-                && (!\ctype_xdigit(\ltrim($request->getData('color') ?? '', '#'))
-                    || \stripos($request->getData('color') ?? '', '#') !== 0)))
+                && (!\ctype_xdigit(\ltrim($request->getData('color'), '#'))
+                    || \stripos($request->getData('color'), '#') !== 0)))
         ) {
             return $val;
         }
@@ -71,7 +71,7 @@ final class ApiController extends Controller
      *
      * @since 1.0.0
      */
-    public function apiTagUpdate(RequestAbstract $request, ResponseAbstract $response, $data = null) : void
+    public function apiTagUpdate(RequestAbstract $request, ResponseAbstract $response, mixed $data = null) : void
     {
         /** @var Tag $old */
         $old = clone TagMapper::get()->where('id', (int) $request->getData('id'))->execute();
@@ -112,7 +112,7 @@ final class ApiController extends Controller
      *
      * @since 1.0.0
      */
-    public function apiTagCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : void
+    public function apiTagCreate(RequestAbstract $request, ResponseAbstract $response, mixed $data = null) : void
     {
         if (!empty($val = $this->validateTagCreate($request))) {
             $response->set('tag_create', new FormValidation($val));
@@ -162,7 +162,7 @@ final class ApiController extends Controller
      *
      * @since 1.0.0
      */
-    public function apiTagL11nCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : void
+    public function apiTagL11nCreate(RequestAbstract $request, ResponseAbstract $response, mixed $data = null) : void
     {
         if (!empty($val = $this->validateTagL11nCreate($request))) {
             $response->set('tag_l11n_create', new FormValidation($val));
@@ -229,7 +229,7 @@ final class ApiController extends Controller
      *
      * @since 1.0.0
      */
-    public function apiTagGet(RequestAbstract $request, ResponseAbstract $response, $data = null) : void
+    public function apiTagGet(RequestAbstract $request, ResponseAbstract $response, mixed $data = null) : void
     {
         /** @var Tag $tag */
         $tag = TagMapper::get()->where('id', (int) $request->getData('id'))->execute();
@@ -249,7 +249,7 @@ final class ApiController extends Controller
      *
      * @since 1.0.0
      */
-    public function apiTagDelete(RequestAbstract $request, ResponseAbstract $response, $data = null) : void
+    public function apiTagDelete(RequestAbstract $request, ResponseAbstract $response, mixed $data = null) : void
     {
         /** @var Tag $tag */
         $tag = TagMapper::get()->where('id', (int) $request->getData('id'))->execute();
@@ -270,7 +270,7 @@ final class ApiController extends Controller
      *
      * @since 1.0.0
      */
-    public function apiTagFind(RequestAbstract $request, ResponseAbstract $response, $data = null) : void
+    public function apiTagFind(RequestAbstract $request, ResponseAbstract $response, mixed $data = null) : void
     {
         $response->header->set('Content-Type', MimeType::M_JSON, true);
         $response->set(
diff --git a/Controller/BackendController.php b/Controller/BackendController.php
index da19545..c63d67c 100755
--- a/Controller/BackendController.php
+++ b/Controller/BackendController.php
@@ -44,7 +44,7 @@ final class BackendController extends Controller
      * @since 1.0.0
      * @codeCoverageIgnore
      */
-    public function viewTagCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
+    public function viewTagCreate(RequestAbstract $request, ResponseAbstract $response, mixed $data = null) : RenderableInterface
     {
         $view = new View($this->app->l11nManager, $request, $response);
 
@@ -66,7 +66,7 @@ final class BackendController extends Controller
      * @since 1.0.0
      * @codeCoverageIgnore
      */
-    public function viewTagList(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
+    public function viewTagList(RequestAbstract $request, ResponseAbstract $response, mixed $data = null) : RenderableInterface
     {
         $view = new View($this->app->l11nManager, $request, $response);
 
@@ -102,15 +102,18 @@ final class BackendController extends Controller
      * @since 1.0.0
      * @codeCoverageIgnore
      */
-    public function viewTagSingle(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
+    public function viewTagSingle(RequestAbstract $request, ResponseAbstract $response, mixed $data = null) : RenderableInterface
     {
         $view = new View($this->app->l11nManager, $request, $response);
-        $tag  = TagMapper::get()->with('title')->where('id', (int) $request->getData('id'))->where('title/language', $response->getLanguage())->execute();
+
+        /** @var \Modules\Tag\Models\Tag $tag */
+        $tag = TagMapper::get()->with('title')->where('id', (int) $request->getData('id'))->where('title/language', $response->getLanguage())->execute();
 
         $view->setTemplate('/Modules/Tag/Theme/Backend/tag-single');
         $view->addData('nav', $this->app->moduleManager->get('Navigation')->createNavigationMid(1007501001, $request, $response));
         $view->addData('tag', $tag);
 
+        /** @var \Modules\Tag\Models\TagL11n[] $l11n */
         $l11n = TagL11nMapper::getAll()->where('tag', $tag->getId())->execute();
         $view->addData('l11n', $l11n);