Error upon adding new list items

Problem/Motivation

On my project with v1.0.1 of required_by_form_mode and Profile module v1.12 installed, I receive ajax errors when trying to add new options to list field during field creation for Profile entities.
I will create a MR with workaround that worked for me but may be not the best solution.

Error trace I see in logs:

InvalidArgumentException: The configuration property settings.allowed_values.0.label.0 doesn't exist. in Drupal\Core\Config\Schema\ArrayElement->get() (regel 95 van /code/web/core/lib/Drupal/Core/Config/Schema/ArrayElement.php).

#0 /code/web/core/lib/Drupal/Core/Config/StorableConfigBase.php(223): Drupal\Core\Config\Schema\ArrayElement->get('settings.allowe...')
#1 /code/web/core/lib/Drupal/Core/Config/StorableConfigBase.php(258): Drupal\Core\Config\StorableConfigBase->castValue('settings.allowe...', Array)
#2 /code/web/core/lib/Drupal/Core/Config/StorableConfigBase.php(258): Drupal\Core\Config\StorableConfigBase->castValue('settings.allowe...', Array)
#3 /code/web/core/lib/Drupal/Core/Config/StorableConfigBase.php(258): Drupal\Core\Config\StorableConfigBase->castValue('settings.allowe...', Array)
#4 /code/web/core/lib/Drupal/Core/Config/StorableConfigBase.php(258): Drupal\Core\Config\StorableConfigBase->castValue('settings.allowe...', Array)
#5 /code/web/core/lib/Drupal/Core/Config/StorableConfigBase.php(258): Drupal\Core\Config\StorableConfigBase->castValue('settings', Array)
#6 /code/web/core/lib/Drupal/Core/Config/Config.php(211): Drupal\Core\Config\StorableConfigBase->castValue(NULL, Array)
#7 /code/web/core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php(278): Drupal\Core\Config\Config->save(false)
#8 /code/web/core/lib/Drupal/Core/Entity/EntityStorageBase.php(486): Drupal\Core\Config\Entity\ConfigEntityStorage->doSave('profile.field_t...', Object(Drupal\field\Entity\FieldStorageConfig))
#9 /code/web/core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php(257): Drupal\Core\Entity\EntityStorageBase->save(Object(Drupal\field\Entity\FieldStorageConfig))
#10 /code/web/core/lib/Drupal/Core/Entity/EntityBase.php(354): Drupal\Core\Config\Entity\ConfigEntityStorage->save(Object(Drupal\field\Entity\FieldStorageConfig))
#11 /code/web/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php(617): Drupal\Core\Entity\EntityBase->save()
#12 /code/web/modules/contrib/required_by_form_mode/required_by_form_mode.module(132): Drupal\Core\Config\Entity\ConfigEntityBase->save()
#13 [internal function]: required_by_form_mode_field_config_edit_form_builder('field_config', Object(Drupal\field\Entity\FieldConfig), Array, Object(Drupal\Core\Form\FormState))
#14 /code/web/core/lib/Drupal/Core/Entity/EntityForm.php(307): call_user_func_array('required_by_for...', Array)
#15 /code/web/core/lib/Drupal/Core/Entity/EntityForm.php(171): Drupal\Core\Entity\EntityForm->buildEntity(Array, Object(Drupal\Core\Form\FormState))
#16 /code/web/core/modules/field_ui/src/Form/FieldConfigEditForm.php(278): Drupal\Core\Entity\EntityForm->afterBuild(Array, Object(Drupal\Core\Form\FormState))
#17 [internal function]: Drupal\field_ui\Form\FieldConfigEditForm->afterBuild(Array, Object(Drupal\Core\Form\FormState))
#18 /code/web/core/lib/Drupal/Core/Form/FormBuilder.php(1082): call_user_func_array(Array, Array)
#19 /code/web/core/lib/Drupal/Core/Form/FormBuilder.php(579): Drupal\Core\Form\FormBuilder->doBuildForm('field_config_ed...', Array, Object(Drupal\Core\Form\FormState))
#20 /code/web/core/lib/Drupal/Core/Form/FormBuilder.php(326): Drupal\Core\Form\FormBuilder->processForm('field_config_ed...', Array, Object(Drupal\Core\Form\FormState))
#21 /code/web/core/lib/Drupal/Core/Entity/EntityFormBuilder.php(48): Drupal\Core\Form\FormBuilder->buildForm(Object(Drupal\field_ui\Form\FieldConfigEditForm), Object(Drupal\Core\Form\FormState))
#22 /code/web/core/modules/field_ui/src/Controller/FieldConfigAddController.php(63): Drupal\Core\Entity\EntityFormBuilder->getForm(Object(Drupal\field\Entity\FieldConfig), 'default', Array)
#23 [internal function]: Drupal\field_ui\Controller\FieldConfigAddController->fieldConfigAddConfigureForm('profile', 'field_test_list')
#24 /code/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(123): call_user_func_array(Array, Array)
#25 /code/web/core/lib/Drupal/Core/Render/Renderer.php(638): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
#26 /code/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(124): Drupal\Core\Render\Renderer->executeInRenderContext(Object(Drupal\Core\Render\RenderContext), Object(Closure))
#27 /code/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(97): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array)
#28 /code/vendor/symfony/http-kernel/HttpKernel.php(181): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
#29 /code/vendor/symfony/http-kernel/HttpKernel.php(76): Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1)
#30 /code/web/modules/contrib/simple_oauth/src/HttpMiddleware/BasicAuthSwap.php(68): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#31 /code/web/core/lib/Drupal/Core/StackMiddleware/Session.php(53): Drupal\simple_oauth\HttpMiddleware\BasicAuthSwap->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#32 /code/web/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(48): Drupal\Core\StackMiddleware\Session->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#33 /code/web/core/lib/Drupal/Core/StackMiddleware/ContentLength.php(28): Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#34 /code/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(116): Drupal\Core\StackMiddleware\ContentLength->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#35 /code/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(90): Drupal\page_cache\StackMiddleware\PageCache->pass(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#36 /code/vendor/asm89/stack-cors/src/Cors.php(53): Drupal\page_cache\StackMiddleware\PageCache->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#37 /code/web/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(48): Asm89\Stack\Cors->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#38 /code/web/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(51): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#39 /code/web/core/lib/Drupal/Core/StackMiddleware/AjaxPageState.php(36): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#40 /code/web/core/lib/Drupal/Core/StackMiddleware/StackedHttpKernel.php(51): Drupal\Core\StackMiddleware\AjaxPageState->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#41 /code/web/core/lib/Drupal/Core/DrupalKernel.php(741): Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#42 /code/web/index.php(19): Drupal\Core\DrupalKernel->handle(Object(Symfony\Component\HttpFoundation\Request))
#43 {main}

Steps to reproduce

Have required_by_form_mode and profile modules installed.
Try to create field of type List for Profile entity type.
Go thru creation steps until options configuration.
Try to add new option

Proposed resolution

Make sure that module's code is not run within ajax requests.

Remaining tasks

Review and test