fix(AdminController): ob_end_clean without content creates error

Author: Kaikina

controllers/admin/AdminConfigureSlidesController.php

@@ -22,7 +22,10 @@ class AdminConfigureSlidesController extends ModuleAdminController
     public function ajaxProcessUpdateSlidesPosition()
     {
         if (empty(Tools::getValue('action')) || Tools::getValue('action') != 'updateSlidesPosition' || empty(Tools::getValue('slides'))) {
-            ob_end_clean();
+			if (ob_get_contents()) {
+	            ob_end_clean();
+	        }
+			
             header('Content-Type: application/json');
             $this->ajaxRender(json_encode(['error' => true]));
             exit;
@@ -40,7 +43,10 @@ public function ajaxProcessUpdateSlidesPosition()
         // Wipe module cache
         $this->module->clearCache();
 
-        ob_end_clean();
+        if (ob_get_contents()) {
+			ob_end_clean();
+		}
+		
         header('Content-Type: application/json');
         $this->ajaxRender(json_encode(['success' => true]));
         exit;