fix PHP Warning for array key wpseo_premium in free plan

[edluis97]

…wpmy/public_html/wp-content/plugins/wordpress-seo/inc/options/class-wpseo-options.php on line 579 - free plan only

Context

Summary

This PR can be summarized in the following changelog entry:

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Test instructions

Test instructions for the acceptance test before the PR gets merged

This PR can be acceptance tested by following these steps:

Relevant test scenarios

• Changes should be tested with the browser console open
• Changes should be tested on different posts/pages/taxonomies/custom post types/custom taxonomies
• Changes should be tested on different editors (Default Block/Gutenberg/Classic/Elementor/other)
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• Changes should be tested on multisite

Test instructions for QA when the code is in the RC

• QA should use the same steps as above.

QA can test this PR by following these steps:

Impact check

This PR affects the following parts of the plugin, which may require extra testing:

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• This PR also affects Shopify. I have added a changelog entry starting with [shopify-seo], added test instructions for Shopify and attached the Shopify label to this PR.

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• I have written documentation for this change. For example, comments in the Relevant technical choices, comments in the code, documentation on Confluence / shared Google Drive / Yoast developer portal, or other.

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Fixes #

[enricobattocchi]

@edluis97 can you give instructions about how to reproduce the issue you are experiencing?

[edluis97]

I'll be honest with you, I'm fairly inexperienced with Yoast, having started using only about a few days ago (and WP too for that matter).

However, since I wanted to display the errors, in order to check my own plugin, I changed my wp-config.php.
Commented define( 'WP_DEBUG', false );
And added

define( 'WP_DEBUG', true );
define( 'WP_DEBUG_DISPLAY', true );
define( 'WP_DEBUG_LOG', true );
@ini_set( 'display_errors', 1 );

I'm using the free version of Yoast, as of now, at least.
I noticed within the plugins list page it was displaying the following warnings that were also stored to my debug.log:

[04-Dec-2025 05:46:35 UTC] PHP Warning:  Undefined array key "wpseo_premium" in MY_WEBSITES_PATH/wp-content/plugins/wordpress-seo/inc/options/class-wpseo-options.php on line 579
[04-Dec-2025 05:46:35 UTC] PHP Warning:  foreach() argument must be of type array|object, null given in MY_WEBSITES_PATH/wp-content/plugins/wordpress-seo/inc/options/class-wpseo-options.php on line 583

I installed yoast through the WordPress repo, btw. My website's running PHP 8.3.26.

Hope this info is useful. Thank you.