Layout builder incompatibility

Can confirm the same results with vanilla 8.8.0-dev and Display Suite 3.3.

Added another problem description as requested by @swentel in #3076819: Display Suite layout is still active after enabling Layout Builder.

This fixes the blank option

And this resets ds layouts when you enable layout builder. it also hides the fieldsets which aren't relevant anymore.

This is weird.
The issue was indirectly linked from core issue #3111761: "Error: Call to undefined method Drupal\Core\Entity\Entity\EntityViewDisplay::isLayoutBuilderEnabled()" after 8.7.10 to 8.8.0 update, via #3078617: WSOD upon enable with Layout Builder.
So I thought it would fix the problem reported there.

But the error message from the linked core issue #3111761: "Error: Call to undefined method Drupal\Core\Entity\Entity\EntityViewDisplay::isLayoutBuilderEnabled()" after 8.7.10 to 8.8.0 update looks like it happened with the code change from this issue already in place:

Error: Call to undefined method
Drupal\Core\Entity\Entity\EntityViewDisplay::isLayoutBuilderEnabled() in
ds_field_ui_fields_layouts()

I just had this happen to me.
Perhaps there are specific scenarios where this happens.

The code snippet in question:

  if (\Drupal::moduleHandler()->moduleExists('layout_builder') && $entity_display->isLayoutBuilderEnabled()) {
    return;
  }

I think the safer thing here would be instanceof, like so:

  if ($entity_display instanceof LayoutBuilderEnabledInterface && $entity_display->isLayoutBuilderEnabled()) {
    return;
  }

Fyi, you can use instanceof with an unknown class:
https://3v4l.org/FgGoP
So this would still work if layout_builder is not enabled.

Hmm, makes sense to check on the interface, reopening.

Should be fine. Code looks more elegant too :)

committed and pushed, added credit too, thanks!

Cool!
Btw with this "early return" pattern, I like to put the comment inside the if(), like so:

  if ($entity_display instanceof LayoutBuilderEnabledInterface && $entity_display->isLayoutBuilderEnabled()) {
    // The view mode is using layout builder.
    // Don't add any ds-related elements to the form in this case.
    return;
  }

This way the comment can be written in plain sentence describing what "is", instead of using a conditional form describing what "would be".

I also wonder if this check should be moved up a bit.
Some of the variables at the top are not really needed for this check.
Or perhaps move it into ds_form_entity_view_display_edit_form_alter()? Not sure. I think we still want the ds_extras modifications to the form even if it is using layout builder.

I'm still seeing this issue with the latest version of DS 3.7 and Drupal core 8.8, when trying to save a display on a content type or any entity.

Error: Call to undefined method Drupal\Core\Entity\Entity\EntityViewDisplay::isLayoutBuilderEnabled() in ds_field_ui_layouts_save() (line 333 of modules/contrib/ds/includes/field_ui.inc).

I have both DS and Layout builder installed and the previous developer has made it very hard to uninstall any one of them without rebuilding a large part of the website.

Edit: I'm not sure if this will break anything but if I change like 333 of field_ui.inc from

if (\Drupal::moduleHandler()->moduleExists('layout_builder') && $display->isLayoutBuilderEnabled()) {

to

if ($display instanceof LayoutBuilderEnabledInterface && $display->isLayoutBuilderEnabled()) {

This seems to fix the error, but I'm not sure if it is ok or not?

If anyone could let me know I would appreciate it.

Crap, we totally forgot that part. That will indeed fix the fatal error.

Here is a patch.

let's see what the bot thinks

Couldn't reproduce the error myself, but the fix makes sense. committed and pushed, thanks!