Fix compatible AssetVariable::offsetGet() between different PHP ver…

…sions

modules/template/models/AssetVariable.php

@@ -9,6 +9,8 @@
  * 
  * A OwnerContent instance is used to assign a TemplateElement to a specific
  * Content of a specific type.
+ *
+ * @warning Compatible only with PHP8.0+, Don't use for PHP versions <= 7.4!
  */
 class AssetVariable implements \ArrayAccess
 {

modules/template/models/AssetVariablePhp74.php

@@ -0,0 +1,62 @@
+<?php
+
+namespace humhub\modules\custom_pages\modules\template\models;
+
+use Yii;
+
+/**
+ * This is the model class for table "custom_pages_template_content".
+ * 
+ * A OwnerContent instance is used to assign a TemplateElement to a specific
+ * Content of a specific type.
+ *
+ * @deprecated Use this only for PHP7.4 and older versions
+ */
+class AssetVariablePhp74 implements \ArrayAccess
+{
+
+    private $module;
+
+    public function get($name)
+    {
+        $path = '/'.$name;
+
+        $module = $this->getModule();
+        if($module->isPublished($path)) {
+            return $this->getModule()->getPublishedUrl($path);
+        }
+        return '';
+    }
+
+    private function getModule()
+    {
+        if($this->module == null) {
+            $this->module = Yii::$app->getModule('custom_pages');
+        }
+        return $this->module;
+    }
+
+    public function __toString()
+    {
+        return '';
+    }
+
+    public function offsetExists($offset): bool
+    {
+        return true;
+    }
+
+    public function offsetGet($offset)
+    {
+        return $this->get($offset);
+    }
+
+    public function offsetSet($offset, $value): void
+    {
+    }
+
+    public function offsetUnset($offset): void
+    {
+    }
+
+}

modules/template/models/Template.php

@@ -207,7 +207,7 @@ public function render(ActiveRecord $owner = null, $editMode = false, $container
             $content[$contentElement->element_name] = new OwnerContentVariable(['ownerContent' => $contentElement, 'options' => $options]);
         }
 
-        $content['assets'] = new AssetVariable();
+        $content['assets'] = PHP_VERSION_ID >= 80000 ? new AssetVariable() : new AssetVariablePhp74();
 
         if($containerItem) {
             //$content['item'] = new ContainerItemVariable(['item' => $containerItem]);