astra-child | Child theme for Astra Theme | Theme library

I MUST maintain this line where she is.

That directive does not need to go inside the WordPress code block. You should place that directive before the # BEGIN WordPress comment marker. And this will prevent it from being overwritten by WordPress. In fact, you could place your custom rules at the very top of the file to make them easier to find/maintain.

It will work exactly the same.

You do not need to enclose it in an container like the other directives. And you should not repeat the RewriteEngine On and RewriteBase / directives. (The order of these particular directives do not matter. In fact, the last instance "wins" and controls the entire file.)

For example:

Seems like at some point that file may get loaded when there are no totals yet. May want to conditionally check for them to avoid the Error message. You can save the totals to a varibale then check to make sure they are not empty and are an array like below:

Since WooCommerce 3, you need to use the WC_coupon method get_code() instead of trying to access the coupon "code" property directly, so you will have to replace in your code:

So, as i didn't get any clear help in this case, here is a clear solution that helped me.

While you didn't post it, you're almost assuredly experiencing a syntax error... reference the actual error notice to know what problem you are running in to. Line numbers aren't that helpful to us for diagnosing the issue since the line numbers in your snippet aren't the same.

You're in the middle of echoing out string text, so you don't open a tag. Removing the two instances where you open and close the PHP tags would probably work. Or since you are directly writing out HTML, I'd probably close the pho tags... print the HTML... then open the PHP tags again for the shortcode reference.