Breadcrumb includes parents that aren't published

[kraftner]

Although rare sometimes a post can have a parent that itself doesn't have status publish. This might occur under (at least) the following conditions:

1. You change the post status of a published post with existing children. The children then for now* still has the post as parent.

2. If you alter the page attributes/parent dropdown to intentionally include e.g. private or draft posts using the page_attributes_dropdown_pages_args and quick_edit_dropdown_pages_args.

* As the page attributes/parent dropdown doesn't list anything but published posts the next time you save any of those children they loose the connection and become a root post themselves. See core issue #8592 for details.

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I think the fix could be this:

if( 'publish' === $post->post_status ) break;

here:

breadcrumb-trail/inc/breadcrumbs.php

Lines 941 to 946 in cd728c5

	// Get the post by ID.
	$post = get_post( $post_id );
	// If we hit a page that's set as the front page, bail.
	if ( 'page' == $post->post_type && 'page' == get_option( 'show_on_front' ) && $post_id == get_option( 'page_on_front' ) )
	break;

What I am a little bit unsure is how to handle private:

if( in_array( $post->post_status, array( 'publish', 'private' ) ) ) break;

I guess there would need to be some further check to see if the user can see it, but I didn't have time yet to look into that. So leaving this as a hint for now which I hope to revisit later.