FIx of Fatal Error: handleProductUpdated() Argument #2 ($post_after) must be of type WP (Issue #1309)

[mabfahad]

Summary

Fixes a fatal error in Mailchimp for WooCommerce when updating or deleting products. WordPress can pass null for $post_after or $post_before in the post_updated hook, but the function signature required WP_Post, causing a TypeError.

Fix

• Updated method signature to accept nullable parameters:

public function handleProductUpdated( int $post_ID, ?WP_Post $post_after, ?WP_Post $post_before )

• Added safeguard inside the function:

if ( ! $post_after instanceof WP_Post ) {
    return;
}

Testing

• Product updates and deletions no longer trigger fatal errors.
• Tested on WordPress 6.x, WooCommerce latest, PHP 8.1/8.2