PHP notices when removing a custom post type which contains posts with attachments

[Chouby]

To reproduce, just create a plugin which registers a certain custom post type. Create a post in this custom post type with some attachments. De-activate the plugin. Go to the media list table.

The title of the just created post is displayed without link in the column "uploaded to" and PHP notices are logged:
Trying to get property of non-object in /wp-includes/capabilities.php on 1116
Same thing for lines 1117, 1120

The problems comes from the fact that after the line 1114
$post_type = get_post_type_object( $post->post_type );
There is no check that the returned post type is valid or not.

In that particular case, I am not sure if we should test for the validity of the post type in the meta_cap function or in the calling function (line 314 in class-wp-media-list-table.php)

[Chouby]

The patch proposed does the correction in class-wp-media-list-table.php

[helen]

Related: #22312

[SergeyBiryukov]

Introduced in [25140].

If the parent post type no longer exists, we should probably show the image as unattached: 26451.2.patch​.

[wonderboymusic]

Yes - this is better and Attach'ing works when the link is clicked.

[wonderboymusic]

We need to also account for this in Media Grid

[wonderboymusic]

Duplicate of #27446.

See [29320]