Hi,
I said that when I replaced these lines as you suggested, it broke the cart. Once I put the original code back, the cart worked fine.
These are errors that are being written to 2 different error_logs. I haven't customized any of the PHP files. I have only added custom CSS settings to the theme.
From the errors, you can plainly see that your PHP files contain outdated WooCommerce functions that need to be replaced just like you said above.
So, please replace these two deprecated functions in your PHP files, test them, and upload them to this ticket once you have them working.
I will replace them on my production site.
Soon, I am going to need to charge you guys for support... :)
Thank you!