Layout builder prevents the rendering of extra fields (like Links) on pages not using Layout Builder

I believe this is due to #3001313: Field blocks in the layout builder do not have view mode suggestions
Leaving postponed instead of closing as a duplicate, for now.

This problem also exists in Drupal 8.6.4.
1. Enable Layout builder module
2. "Add child page" and "Printer-friendly version" are absent

I am trying to uninstall layout builder but ran into this issue:
Layout Builder cannot be uninstalled while overrides exist; no easy way to revert all overrides

I also see this in the comment links.
I think the problem extends to all fields-links.

Oh, I made some very incorrect assumptions about the steps to reproduce. I was enabling Layout Builder for Book nodes, which works fine. The problem is when Layout Builder is NOT enabled.

This is also reproducible without Book module: node teasers have "Read more" links

Here's a fix. The current conditional will always be TRUE when the module is installed, regardless of configuration.

The patch doesn't work, causes an error.
I think needed use empty().

Deleted unnecessary

What error does it cause?
That patch will not work since the array will always contain #cache information and will never be empty

Oh it will be an undefined index error in some cases. Okay, working on this now.

Needs the isset() for sure in 8.6, less important in 8.7 but still worth having.

Test addition conflicted with #2938132: Ship layouts that make sense with Layout Builder's concept of sections.
Interdiff was correct though.

#13 works.
TNX. Good job!

Glad to hear it. Ready for final review!

+++ b/core/modules/layout_builder/layout_builder.module
@@ -106,7 +106,7 @@ function layout_builder_field_config_delete(FieldConfigInterface $field_config)
-  if ($display instanceof LayoutEntityDisplayInterface) {
+  if (isset($build['_layout_builder']) && !Element::isEmpty($build['_layout_builder'])) {

Add comment describing what the conditional is checking

Ahh good point, knowing where that '_layout_builder' string comes from would be tricky without a comment.

Reviewed and tested:

• Without Layout Builder enabled, created a new book page (worth noting I also chose "Create a new book" in the Book Outline tab, which was necessary to make "Add child page" and "Printer-friendly version" visible on this book page.
  - Enabled Layout
• Enabled Layout builder, cleared cache, and verified that "Add child page" and "Printer-friendly version" were no longer present
• Applied 3007973-extrafields-18.patch, cleared cache then confirmed that "Add child page" and "Printer-friendly version" were again visible
• Reviewed code and concluded it is quite easy to follow, with comment was added in the single spot where further explanation might be helpful
• Checked the new testExtraFields() test pre and post-patch.

Thanks! Update the IS to include the non-book module approach to reproduce.

This looks like a straight-up bugfix with no disruptions and @stompersly documented that it also exists in 8.6.4, so it should be backported.

Sending for an 8.6.x test run.

Moving the method higher up in the class so it applies to 8.6 and 8.7

Committed to 8.7.x and cherry-picked to 8.6.x. Thanks!

I added issue credit for @stompersly since the comment helped me notice it should be backported. :)

In core version 8.6.9 the patch in #22 dont apply.

I think is due to different line numbers in the file layout_builder.module

The patch has already been committed in 8.6.8
https://www.drupal.org/project/drupal/releases/8.6.8