PHP Warning: Undefined array key 0 in .../wp-includes/meta.php on line 651

[wpSight]

I have WordPress 6.8-beta3-60069 with PHP 8.3 installed.

When I use get_post_meta() with a not existing beta key for the current post the warning

Warning: Undefined array key 0 in wp-includes\meta.php on line 651

appears.

This messages is realted to return $check[0];
$check is an array, but empty. Thats why the key [0] does not exist.

You can check with a random request

$duration = get_post_meta( $post_id, 'random_key', true );

[wpSight]

No need to check. Issue is related to a third-party product which manipulates the meta key.