You can you submit a new ticket for that https://support.advancedcustomfields.com/new-ticket/. But the problem isn’t that there is a non-existent post, the problem is that the value is not set at all. Here is an example:
this location rule will not create an error, but it can never be met since there will never be a post with an ID of 0
// .....
'location' => array (
array (
array (
'param' => 'post',
'operator' => '==',
'value' => '0',
),
),
),
// .....
However, this location rule will cause the error you posted because the value parameter is not included
// .....
'location' => array (
array (
array (
'param' => 'post',
'operator' => '==',
),
),
),
// .....
