Block Form Fails on Content Type Layout Builder Page

Problem/Motivation

When attempting to place a patternkit block on a default layout for a Node, the form fails to load and an AJAX error is returned with no visible feedback. In the logs, the following error message is recorded:

Drupal\Core\Entity\EntityMalformedException: The "node" entity cannot have a URI as it does not have an ID in Drupal\Core\Entity\EntityBase->toUrl() (line 161 of /var/www/html/web/core/lib/Drupal/Core/Entity/EntityBase.php).

Steps to reproduce

1. Enable the patternkit and patternkit_example modules
2. Create a node type with layout builder enabled
3. Edit the default layout for the node type
4. Attempt to add a patternkit block into one of the sections
5. (X) Observe no response when clicking the pattern name
6. View the site logs and observe the error message described above

Proposed resolution

After some digging, this appears to be caused by the token listing on the edit form which attempts to render the token value to display as an example. When the [node:url] and [node:edit-url] tokens are rendered, the logged exception is thrown because the Node being rendered doesn't have an ID yet.

To address this, I suggest wrapping the rendering of the token for this example value in a try/catch and excluding the example value if it fails.

Remaining tasks

• Review and testing

User interface changes

The block form token listing excludes examples for tokens that cannot be rendered for the current context.

API changes

None

Data model changes

None