All Submissions:

• Have you followed the WooCommerce Contributing guideline?
• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

This PR adds error handling to the WooCommerce > Subscriptions (experiment) page if the "Get Started" buttons fails to install WooCommerce Payments.

part of #32694

How to test the changes in this Pull Request:

0. Checkout this branch and run pnpm nx build-watch woocommerce-admin to build assets
1. Add the 'DISALLOW_FILE_MODS' const to your site (see example below).
2. With WooCommerce Payments and WooCommerce Subscriptions inactive, navigate to WooCommerce > Subscriptions
3. Click the "Get started" button.
4. Once the plugin activation is attempted, you should see the following error message.

define( 'DISALLOW_FILE_MODS', true );

Note: without the DISALLOW_FILE_MODS set to true, the "Get started" button will install (if necessary) and activate WooCommerce Payments but the page will appear to hang and the button will be stuck on processing. This is intended for now and will be handled by the rest of #32694 once the experiment allocation is settled.

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully run tests with your changes locally?
• Have you created a changelog file by running pnpm nx affected --target=changelog?

FOR PR REVIEWER ONLY:

• I have reviewed that everything is sanitized/escaped appropriately for any SQL or XSS injection possibilities. I made sure Linting is not ignored or disabled.