WC_Frontend_Scripts error message

this is a warning , can be safely ignored if rest of website works fine.

it looks ugly on homepage though, you can turn wp_debug to false to remove the annonying message.

https://codex.www.ads-software.com/Debugging_in_WordPress

wp_debug is currently set to FALSE in my wp-config file, and the error still shows up

quite strange , diasbling it normally takes the warnings off the site.

i am not sure but you can try the solution mentioned here
https://stackoverflow.com/questions/15949304/turn-off-display-error-php-ini this goes into your php.ini , now if you are on shared host then this will again be a issue.

working solution for this will be to reinstall wordress.
download and upload latest version of wordpress. make backup of wp-config.php file and wp-config folder. other files/folders can be replaced with the files you downloaded from wordpress.

https://codex.www.ads-software.com/Installing_WordPress

do take full database and file backup before trying this.

I know its frustrasting

please follow these instructions carefully. take proper backups and you can fix it.