Polylang Integration Issue After Website Migration

I am facing an issue after migrating our website from devicesa.com to intouchclinic.com.

Upon completing the migration, an error is showing on every page, manifesting as follows: “Warning: Undefined array key ‘default_lang’ in /home1/intouch4/public_html/wp-content/plugins/polylang-1/include/links-directory.php on line 69.” You can check the screenshot here.

To facilitate your investigation, a demo account has been created for your convenience, accessible with the following credentials:

• Username: demo
• Password: demo

I have deactivated of all plugins and experimented with different WordPress versions. Unfortunately, the error is still there, and I am seeking your guidance to resolve this issue

The page I need help with: [log in to see the link]