Layout builder cannot recover on missing layout

This is potentially related to https://www.drupal.org/project/drupal/issues/2860346 🐛 Reset plugin discovery when a module/theme is installed Needs work

The definitions are cached during a theme install.

If a theme provides custom layouts and has configuration objects that use those layouts (like `entity_view_display`), the layouts plugin definitions will already be cached and newly installed layouts will not have a chance to be discovered during the process of the theme installation.

Adding a cache tag that depends on installed extensions resolve this issue.

In LayoutPluginManager:
$this->setCacheBackend($cache_backend, $type, ['config:core.extension']);

Patch attached.

For me #20 doesn't work.
I have a theme that is already installed, and some configs using it (in config_sync).
When I change a layout machine name and attempt to clear cache and config import, it fails.
#16 and #3 are working though.

#20 worked for me on a fresh install with CivicTheme 1.6.2 on Drupal Core 10.2.3. Thanks!

I used patch #20 on Drupal 10.3.0 and CivicTheme 1.7.1 and the fatal error went away.

It would be great if someone wanted to review the different approach in #20, update the issue summary, and add tests :)