I’m working on a Shopware 6 plugin and encountering a warning related to accessing an array key that doesn’t exist. Here’s the relevant code snippet:

$customFields = $order->getCustomFields();
$optin = null;
if (array_key_exists('swag_product_reviews_optin', $customFields)) {
    $optin = $customFields['swag_product_reviews_optin'];
}
$text .= '  » Optin: ' . $optin;

As you can see, I’m checking if the ‘swag_product_reviews_optin’ key exists in the $customFields array before attempting to access it. However, I’m still getting the following warning:

Warning: Undefined array key "swag_product_reviews_optin"

Here’s the full stack trace:

#0 /home/wokljnlu/sw66demo.wo-kaufen.de/vendor/symfony/http-kernel/HttpKernel.php(178): SwagProductReviewsAdministrationControllerSwagProductReviewsTestMailController->orderWhyNot()
#1 /home/wokljnlu/sw66demo.wo-kaufen.de/vendor/symfony/http-kernel/HttpKernel.php(76): SymfonyComponentHttpKernelHttpKernel->handleRaw()
...

I’m not sure what could be causing this warning, as the code seems to be correctly checking for the key’s existence before accessing it.
My question is:
What could be causing this “Undefined array key” warning in Shopware 6, even though I’m checking for the key’s existence before accessing it? Is there something I’m missing or a better way to handle this scenario?

This code is executed in a controller action when an admin user triggers a specific route.