RuntimeException when trying to add a new language

Problem/Motivation

I am well aware that it is not possible to add a new language while you are switched to for example the stage workspace - i just had to look up and test something. but the problem is if you are trying to add for example a content type or save any configuration form, they fail gracefully, while when i am trying to add a new language i am running into the following runtime exception:

The website encountered an unexpected error. Try again later.

RuntimeException: This entity can only be saved in the default workspace. in Drupal\workspaces\EntityOperations->entityPresave() (line 132 of core/modules/workspaces/src/EntityOperations.php).
workspaces_entity_presave()
call_user_func_array() (Line: 416)
Drupal\Core\Extension\ModuleHandler->Drupal\Core\Extension\{closure}() (Line: 395)
Drupal\Core\Extension\ModuleHandler->invokeAllWith() (Line: 415)
Drupal\Core\Extension\ModuleHandler->invokeAll() (Line: 325)
Drupal\Core\Config\Entity\ConfigEntityStorage->invokeHook() (Line: 529)
Drupal\Core\Entity\EntityStorageBase->doPreSave() (Line: 483)
Drupal\Core\Entity\EntityStorageBase->save() (Line: 239)
Drupal\Core\Config\Entity\ConfigEntityStorage->save() (Line: 354)
Drupal\Core\Entity\EntityBase->save() (Line: 617)
Drupal\Core\Config\Entity\ConfigEntityBase->save() (Line: 293)
Drupal\Core\Entity\EntityForm->save() (Line: 88)
Drupal\language\Form\LanguageAddForm->save()
call_user_func_array() (Line: 105)
Drupal\Core\Form\FormSubmitter->executeSubmitHandlers() (Line: 43)
Drupal\Core\Form\FormSubmitter->doSubmitForm() (Line: 589)
Drupal\Core\Form\FormBuilder->processForm() (Line: 321)
Drupal\Core\Form\FormBuilder->buildForm() (Line: 73)
Drupal\Core\Controller\FormController->getContentResult() (Line: 39)
Drupal\layout_builder\Controller\LayoutBuilderHtmlEntityFormController->getContentResult() (Line: 80)
Drupal\workspaces\Controller\WorkspacesHtmlEntityFormController->getContentResult()
call_user_func_array() (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 593)
Drupal\Core\Render\Renderer->executeInRenderContext() (Line: 121)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext() (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 183)
Symfony\Component\HttpKernel\HttpKernel->handleRaw() (Line: 76)
Symfony\Component\HttpKernel\HttpKernel->handle() (Line: 53)
Drupal\Core\StackMiddleware\Session->handle() (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle() (Line: 28)
Drupal\Core\StackMiddleware\ContentLength->handle() (Line: 32)
Drupal\big_pipe\StackMiddleware\ContentLength->handle() (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass() (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle() (Line: 50)
Drupal\ban\BanMiddleware->handle() (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle() (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle() (Line: 36)
Drupal\Core\StackMiddleware\AjaxPageState->handle() (Line: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle() (Line: 709)
Drupal\Core\DrupalKernel->handle() (Line: 19) 

Steps to reproduce

• switch to the stage workspace
• go to admin/config/regional/language/add and add another language

Proposed resolution

Avoid the runtime exception and return an error message that this form can only be submitted in the default workspace

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet