Update fixes-dates.php

[callmeahmedr]

Here's the updated line: $post_id = (is_object($post) && isset($post->ID)) ? $post->ID : null;

This change adds a check to ensure $post is an object before accessing its ID property. If $post is not an object, $post_id will be set to null, avoiding the warning.

Previously $post->ID was being accessed, but it appears that $post might be an integer or something other than an object, leading to the warning.

$post_id = ! empty( $post ) ? $post->ID : null;

[man4toman]

Nice catch, thanks @callmeahmedr