Fix Uncaught Error: Call to undefined function Magefan\Blog\Model\is_countable

Author: ihorvansach

Model/TemplatePool.php

@@ -52,7 +52,9 @@ public function getAll(string $templateType):array
      */
     public function getTemplate(string $templateType, string $name):string
     {
-        if (isset($this->templates[$templateType]) && is_countable($this->templates[$templateType])) {
+        if (isset($this->templates[$templateType]) &&
+            (is_array($this->templates[$templateType]) || $this->templates[$templateType] instanceof Countable)
+        ) {
             foreach ($this->templates[$templateType] as $item) {
                 if (isset($item['value']) && $item['value'] == $name) {
                     return $item['template'];