PHP Notice "Undefined variable: screen" in meta-boxes.php:1365

[dmccan]

When going to create a new Wiki post I receive the notice:

NOTICE: E:\laragon\www\betatest\wp-admin\includes\meta-boxes.php:1365 - Undefined variable: screen
include('E:\laragon\www\betatest\wp-admin\edit-form-advanced.php'), register_and_do_post_meta_boxes

To Reproduce
Steps to reproduce the behavior:

• Install the latest version 5 beta

• Install and activate the plugin Yada Wiki from the WP directory

• With debug set to true, go to the Admin menu "Wiki Pages -> Add New" and you should see the warning notice.

• In the file \wp-content\plugins\yada-wiki\includes\register-wiki-cpt.php change line 40 from this:

'supports'  => array( 'title', 'editor', 'author', 'thumbnail', 'revisions', 'publicize', 'wpcom-markdown' ),

To this (adding support for custom fields) to have the notice go away:

'supports'   => array( 'title', 'editor', 'author', 'thumbnail', 'revisions', 'publicize', 'wpcom-markdown', 'custom-fields' ),

Expected behavior
There is no warning notice when using WP 4.9.8. Expect the same with WP 5

Additional context

• Using the default WP theme.
• The only other plugins activated are WordPress Beta Tester and Debug Bar

[ocean90]

Thanks for the report! I have reopened the related core ticket #45257.