diff --git a/Admin/Install/Navigation.php b/Admin/Install/Navigation.php
index e53d2ae..c5c3b54 100644
--- a/Admin/Install/Navigation.php
+++ b/Admin/Install/Navigation.php
@@ -36,7 +36,7 @@ class Navigation
      *
      * @since  1.0.0
      */
-    public static function install(string $path = null, DatabasePool $dbPool = null) : void
+    public static function install(string $path, DatabasePool $dbPool) : void
     {
         \Modules\Navigation\Admin\Installer::installExternal($dbPool, ['path' => __DIR__ . '/Navigation.install.json']);
     }
diff --git a/Controller/ApiController.php b/Controller/ApiController.php
index 25cb077..38acd99 100644
--- a/Controller/ApiController.php
+++ b/Controller/ApiController.php
@@ -182,8 +182,6 @@ final class ApiController extends Controller
                 $tcoll['js'] = $tMedia;
             } elseif (StringUtils::endsWith($lowerPath, '.sqlite') || StringUtils::endsWith($lowerPath, '.db')) {
                 $tcoll['db'][] = $tMedia;
-            } else {
-                // Do nothing; only the creator knows how to deal with this type of file :)
             }
         }
 
diff --git a/Controller/BackendController.php b/Controller/BackendController.php
index a7400b4..2e3f8ca 100644
--- a/Controller/BackendController.php
+++ b/Controller/BackendController.php
@@ -25,6 +25,7 @@ use Modules\Helper\Models\TemplateMapper;
 
 use phpOMS\Account\PermissionType;
 use phpOMS\Asset\AssetType;
+use phpOMS\Contract\RenderableInterface;
 use phpOMS\DataStorage\Database\Query\Builder;
 use phpOMS\Message\Http\RequestStatusCode;
 use phpOMS\Message\RequestAbstract;
@@ -57,12 +58,12 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable
+     * @return RenderableInterface
      *
      * @since  1.0.0
      * @codeCoverageIgnore
      */
-    public function viewTemplateList(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewTemplateList(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -80,12 +81,12 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable
+     * @return RenderableInterface
      *
      * @since  1.0.0
      * @codeCoverageIgnore
      */
-    public function viewTemplateCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewTemplateCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -104,12 +105,12 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable
+     * @return RenderableInterface
      *
      * @since  1.0.0
      * @codeCoverageIgnore
      */
-    public function viewReportCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewReportCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -128,14 +129,14 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable
+     * @return RenderableInterface
      *
      * @throws \Exception
      *
      * @since  1.0.0
      * @codeCoverageIgnore
      */
-    public function viewHelperReport(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewHelperReport(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
         //$file = preg_replace('([^\w\s\d\-_~,;:\.\[\]\(\).])', '', $template->getName());
@@ -171,15 +172,13 @@ final class BackendController extends Controller
             } elseif (StringUtils::endsWith($lowerPath, '.css')) {
                 $tcoll['css'] = $tMedia;
 
-                /** @var Head $head */
+                /** @var \phpOMS\Model\Html\Head $head */
                 $head = $response->get('Content')->getData('head');
                 $head->addAsset(AssetType::CSS, $request->getUri()->getBase() . $tMedia->getPath());
             } elseif (StringUtils::endsWith($lowerPath, '.js')) {
                 $tcoll['js'] = $tMedia;
             } elseif (StringUtils::endsWith($lowerPath, '.sqlite') || StringUtils::endsWith($lowerPath, '.db')) {
                 $tcoll['db'][] = $tMedia;
-            } else {
-                // Do nothing; only the creator knows how to deal with this type of file :)
             }
         }
 
diff --git a/Models/TemplateMapper.php b/Models/TemplateMapper.php
index 6f2f824..34d5366 100644
--- a/Models/TemplateMapper.php
+++ b/Models/TemplateMapper.php
@@ -72,7 +72,7 @@ final class TemplateMapper extends DataMapperAbstract
     /**
      * Has many relation.
      *
-     * @var array<string, array<string, string>>
+     * @var array<string, array<string, null|string>>
      * @since 1.0.0
      */
     protected static $hasMany = [