A PHP Error was encountered

Severity: Warning

Message: Undefined array key "user_id"

Filename: pages/product-page.php

Line Number: 728

Backtrace:

File: /home/dijiyon/public_html/eshop/application/views/front-end/classic/pages/product-page.php
Line: 728
Function: _error_handler

File: /home/dijiyon/public_html/eshop/application/views/front-end/classic/template.php
Line: 74
Function: view

File: /home/dijiyon/public_html/eshop/application/controllers/Products.php
Line: 550
Function: view

File: /home/dijiyon/public_html/eshop/index.php
Line: 315
Function: require_once