Use the framework.

src/Bundle/Resources/config/services.yml

@@ -39,6 +39,8 @@ services:
 
   netzmacht.contao_leaflet.frontend.value_filter:
     class: Netzmacht\Contao\Leaflet\Frontend\ValueFilter
+    arguments:
+      - '@contao.framework'
 
   netzmacht.contao_leaflet.map.assets:
     class: Netzmacht\Contao\Leaflet\Encoder\ContaoAssets

src/Frontend/ValueFilter.php

@@ -12,7 +12,8 @@
 
 namespace Netzmacht\Contao\Leaflet\Frontend;
 
-use Contao\Controller;
+use Contao\CoreBundle\Framework\ContaoFrameworkInterface as ContaoFramework;
+use Contao\InsertTags;
 
 /**
  * Class ValueFilter is a service class which can be used to filter values before passing them to an definition object.
@@ -21,6 +22,45 @@ use Contao\Controller;
  */
 class ValueFilter
 {
+    /**
+     * Contao framework.
+     *
+     * @var ContaoFramework
+     */
+    private $framework;
+
+    /**
+     * Insert tags.
+     *
+     * @var InsertTags
+     */
+    private $replacer;
+
+    /**
+     * ValueFilter constructor.
+     *
+     * @param ContaoFramework $framework Contao framework.
+     */
+    public function __construct(ContaoFramework $framework)
+    {
+        $this->framework = $framework;
+    }
+
+    /**
+     * Get the replacer.
+     *
+     * @return InsertTags
+     */
+    private function getReplacer(): InsertTags
+    {
+        if ($this->replacer === null) {
+            $this->framework->initialize();
+            $this->replacer = $this->framework->createInstance(InsertTags::class);
+        }
+
+        return $this->replacer;
+    }
+
     /**
      * Filter a value so it can be passed to the frontend.
      *
@@ -33,6 +73,6 @@ class ValueFilter
      */
     public function filter($value)
     {
-        return Controller::replaceInsertTags($value);
+        return $this->getReplacer()->replace($value);
     }
 }