Experimental "Layout Paragraphs Builder" field widget overwrites original language when saving translation

Added test for front end builder which checks translations management, found also issues with symmetric translation setup, so added fixes as well, please check and let me know if anything

Hi @sickness29

We were getting the following errors after your last commit:
InvalidArgumentException: Invalid translation language (it) specified. in Drupal\Core\Entity\ContentEntityBase->getTranslation() (line 903 of core/lib/Drupal/Core/Entity/ContentEntityBase.php).
Drupal\layout_paragraphs\LayoutParagraphsLayout->getEntities() (Line: 275)
Drupal\layout_paragraphs\LayoutParagraphsLayout->getComponents() (Line: 246)
Drupal\layout_paragraphs\LayoutParagraphsLayout->getLayoutSection(Object) (Line: 74)
Drupal\layout_paragraphs\LayoutParagraphsRendererService->renderLayoutSection(Array, Object, 'default') (Line: 273)
Drupal\layout_paragraphs\Plugin\paragraphs\Behavior\LayoutParagraphsBehavior->view(Array, Object, Object, 'default') (Line: 42)

So I added a guard for the getTranslation() you added to prevent this error from happening. Whenever a getTranslation() is called it should always be checked if the translations exists by doing a hasTranslation() to prevent the above error.

I experience this exact issue: if the paragraphs on the secondary language are edited in the front end editor (Experimental Layout Paragraphs Builder), all paragraphs on the original language are gone and overridden by the paragraphs on the secondary language.

I'm using 2.1, and seen this issue in 2.2. Is there any fix for these versions?

Created a quick and dirty patch for 2.2.x (installed dev-2.2.x c97badf) based on the changes in https://git.drupalcode.org/project/layout_paragraphs/-/merge_requests/11...

Seems to work for me.

Added a patch for 2.1 as 2.2 has a bug where dragging sub items is not working (not sure how to reproduce it however).