Merge pull request #5 from tafid/fix_additioanl_page_logic

Fix additional page render, check if file exists

src/components/AdditionalPage.php

@@ -69,6 +69,10 @@ public function getLabel(): string
      */
     public function render(array $params = []): string
     {
-        return Yii::$app->view->renderFile($this->pathToPage, array_merge($this->params, $params));
+        if (is_file($this->pathToPage)) {
+            return Yii::$app->view->renderFile($this->pathToPage, array_merge($this->params, $params));
+        }
+
+        return '';
     }
 }