Module breaks creation of new fields

Problem/Motivation

With this module installed, I cannot add new fields to either Node or Taxonomy term entities with Drupal UI.

I have Drupal Core 10.3.6 installed with 1.0.0 version of required_by_form_mode.

Idk if that relevant, but see attached screenshot about how tooltip looks like on edit form of new field:

Couple of log message I receive per field save:

#0 /app/web/core/modules/field/src/Entity/FieldStorageConfig.php(335): Drupal\Core\Config\Entity\ConfigEntityBase->preSave(Object(Drupal\field\FieldStorageConfigStorage))
#1 /app/web/core/lib/Drupal/Core/Entity/EntityStorageBase.php(528): Drupal\field\Entity\FieldStorageConfig->preSave(Object(Drupal\field\FieldStorageConfigStorage))
#2 /app/web/core/lib/Drupal/Core/Entity/EntityStorageBase.php(483): Drupal\Core\Entity\EntityStorageBase->doPreSave(Object(Drupal\field\Entity\FieldStorageConfig))
#3 /app/web/core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php(257): Drupal\Core\Entity\EntityStorageBase->save(Object(Drupal\field\Entity\FieldStorageConfig))
#4 /app/web/core/lib/Drupal/Core/Entity/EntityBase.php(354): Drupal\Core\Config\Entity\ConfigEntityStorage->save(Object(Drupal\field\Entity\FieldStorageConfig))
#5 /app/web/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php(614): Drupal\Core\Entity\EntityBase->save()
#6 /app/web/modules/contrib/required_by_form_mode/required_by_form_mode.module(124): Drupal\Core\Config\Entity\ConfigEntityBase->save()
#7 [internal function]: required_by_form_mode_field_config_edit_form_builder('field_config', Object(Drupal\field\Entity\FieldConfig), Array, Object(Drupal\Core\Form\FormState))
#8 /app/web/core/lib/Drupal/Core/Entity/EntityForm.php(307): call_user_func_array('required_by_for...', Array)
#9 /app/web/core/modules/field_ui/src/Form/FieldConfigEditForm.php(374): Drupal\Core\Entity\EntityForm->buildEntity(Array, Object(Drupal\Core\Form\FormState))
#10 [internal function]: Drupal\field_ui\Form\FieldConfigEditForm->validateForm(Array, Object(Drupal\Core\Form\FormState))
#11 /app/web/core/lib/Drupal/Core/Form/FormValidator.php(82): call_user_func_array(Array, Array)
#12 /app/web/core/lib/Drupal/Core/Form/FormValidator.php(274): Drupal\Core\Form\FormValidator->executeValidateHandlers(Array, Object(Drupal\Core\Form\FormState))
#13 /app/web/core/lib/Drupal/Core/Form/FormValidator.php(118): Drupal\Core\Form\FormValidator->doValidateForm(Array, Object(Drupal\Core\Form\FormState), 'field_config_ed...')
#14 /app/web/core/lib/Drupal/Core/Form/FormBuilder.php(593): Drupal\Core\Form\FormValidator->validateForm('field_config_ed...', Array, Object(Drupal\Core\Form\FormState))
#15 /app/web/core/lib/Drupal/Core/Form/FormBuilder.php(326): Drupal\Core\Form\FormBuilder->processForm('field_config_ed...', Array, Object(Drupal\Core\Form\FormState))
#16 /app/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))
#17 /app/web/core/modules/field_ui/src/Controller/FieldConfigAddController.php(63): Drupal\Core\Entity\EntityFormBuilder->getForm(Object(Drupal\field\Entity\FieldConfig), 'default', Array)
#18 [internal function]: Drupal\field_ui\Controller\FieldConfigAddController->fieldConfigAddConfigureForm('node', 'field_test4')
#19 /app/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(123): call_user_func_array(Array, Array)
#20 /app/web/core/lib/Drupal/Core/Render/Renderer.php(638): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
#21 /app/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(124): Drupal\Core\Render\Renderer->executeInRenderContext(Object(Drupal\Core\Render\RenderContext), Object(Closure))
#22 /app/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(97): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array)
#23 /app/vendor/symfony/http-kernel/HttpKernel.php(181): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
#24 /app/vendor/symfony/http-kernel/HttpKernel.php(76): Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1)
#25 /app/web/modules/contrib/simple_oauth/src/HttpMiddleware/BasicAuthSwap.php(68): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#26 /app/web/core/lib/Drupal/Core/StackMiddleware/Session.php(53): Drupal\simple_oauth\HttpMiddleware\BasicAuthSwap->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#27 /app/web/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(48): Drupal\Core\StackMiddleware\Session->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#28 /app/web/core/lib/Drupal/Core/StackMiddleware/ContentLength.php(28): Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#29 /app/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(106): Drupal\Core\StackMiddleware\ContentLength->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#30 /app/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(85): Drupal\page_cache\StackMiddleware\PageCache->pass(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#31 /app/vendor/asm89/stack-cors/src/Cors.php(53): Drupal\page_cache\StackMiddleware\PageCache->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#32 /app/web/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(48): Asm89\Stack\Cors->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#33 /app/web/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(51): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#34 /app/web/core/lib/Drupal/Core/StackMiddleware/AjaxPageState.php(36): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#35 /app/web/core/lib/Drupal/Core/StackMiddleware/StackedHttpKernel.php(51): Drupal\Core\StackMiddleware\AjaxPageState->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#36 /app/web/core/lib/Drupal/Core/DrupalKernel.php(741): Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#37 /app/web/index.php(19): Drupal\Core\DrupalKernel->handle(Object(Symfony\Component\HttpFoundation\Request))
#38 {main}

Deprecated function: mb_strtolower(): Passing null to parameter #1 ($string) of type string is deprecated in Drupal\Core\Config\Entity\Query\Condition->compile() (regel 39 van /app/web/core/lib/Drupal/Core/Config/Entity/Query/Condition.php)
#0 /app/web/core/includes/bootstrap.inc(166): _drupal_error_handler_real(8192, 'mb_strtolower()...', '/app/web/core/l...', 39)
#1 [internal function]: _drupal_error_handler(8192, 'mb_strtolower()...', '/app/web/core/l...', 39)
#2 /app/web/core/lib/Drupal/Core/Config/Entity/Query/Condition.php(39): mb_strtolower(NULL)
#3 /app/web/core/lib/Drupal/Core/Config/Entity/Query/Query.php(88): Drupal\Core\Config\Entity\Query\Condition->compile(Array)
#4 /app/web/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php(307): Drupal\Core\Config\Entity\Query\Query->execute()
#5 /app/web/core/modules/field/src/Entity/FieldStorageConfig.php(335): Drupal\Core\Config\Entity\ConfigEntityBase->preSave(Object(Drupal\field\FieldStorageConfigStorage))
#6 /app/web/core/lib/Drupal/Core/Entity/EntityStorageBase.php(528): Drupal\field\Entity\FieldStorageConfig->preSave(Object(Drupal\field\FieldStorageConfigStorage))
#7 /app/web/core/lib/Drupal/Core/Entity/EntityStorageBase.php(483): Drupal\Core\Entity\EntityStorageBase->doPreSave(Object(Drupal\field\Entity\FieldStorageConfig))
#8 /app/web/core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php(257): Drupal\Core\Entity\EntityStorageBase->save(Object(Drupal\field\Entity\FieldStorageConfig))
#9 /app/web/core/lib/Drupal/Core/Entity/EntityBase.php(354): Drupal\Core\Config\Entity\ConfigEntityStorage->save(Object(Drupal\field\Entity\FieldStorageConfig))
#10 /app/web/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php(614): Drupal\Core\Entity\EntityBase->save()
#11 /app/web/modules/contrib/required_by_form_mode/required_by_form_mode.module(123): Drupal\Core\Config\Entity\ConfigEntityBase->save()
#12 [internal function]: required_by_form_mode_field_config_edit_form_builder('field_config', Object(Drupal\field\Entity\FieldConfig), Array, Object(Drupal\Core\Form\FormState))
#13 /app/web/core/lib/Drupal/Core/Entity/EntityForm.php(307): call_user_func_array('required_by_for...', Array)
#14 /app/web/core/modules/field_ui/src/Form/FieldConfigEditForm.php(374): Drupal\Core\Entity\EntityForm->buildEntity(Array, Object(Drupal\Core\Form\FormState))
#15 [internal function]: Drupal\field_ui\Form\FieldConfigEditForm->validateForm(Array, Object(Drupal\Core\Form\FormState))
#16 /app/web/core/lib/Drupal/Core/Form/FormValidator.php(82): call_user_func_array(Array, Array)
#17 /app/web/core/lib/Drupal/Core/Form/FormValidator.php(274): Drupal\Core\Form\FormValidator->executeValidateHandlers(Array, Object(Drupal\Core\Form\FormState))
#18 /app/web/core/lib/Drupal/Core/Form/FormValidator.php(118): Drupal\Core\Form\FormValidator->doValidateForm(Array, Object(Drupal\Core\Form\FormState), 'field_config_ed...')
#19 /app/web/core/lib/Drupal/Core/Form/FormBuilder.php(593): Drupal\Core\Form\FormValidator->validateForm('field_config_ed...', Array, Object(Drupal\Core\Form\FormState))
#20 /app/web/core/lib/Drupal/Core/Form/FormBuilder.php(326): Drupal\Core\Form\FormBuilder->processForm('field_config_ed...', Array, Object(Drupal\Core\Form\FormState))
#21 /app/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 /app/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('node', 'field_test')
#24 /app/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(123): call_user_func_array(Array, Array)
#25 /app/web/core/lib/Drupal/Core/Render/Renderer.php(638): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
#26 /app/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(124): Drupal\Core\Render\Renderer->executeInRenderContext(Object(Drupal\Core\Render\RenderContext), Object(Closure))
#27 /app/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(97): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array)
#28 /app/vendor/symfony/http-kernel/HttpKernel.php(181): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
#29 /app/vendor/symfony/http-kernel/HttpKernel.php(76): Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1)
#30 /app/web/modules/contrib/simple_oauth/src/HttpMiddleware/BasicAuthSwap.php(68): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#31 /app/web/core/lib/Drupal/Core/StackMiddleware/Session.php(53): Drupal\simple_oauth\HttpMiddleware\BasicAuthSwap->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#32 /app/web/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(48): Drupal\Core\StackMiddleware\Session->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#33 /app/web/core/lib/Drupal/Core/StackMiddleware/ContentLength.php(28): Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#34 /app/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(106): Drupal\Core\StackMiddleware\ContentLength->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#35 /app/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(85): Drupal\page_cache\StackMiddleware\PageCache->pass(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#36 /app/vendor/asm89/stack-cors/src/Cors.php(53): Drupal\page_cache\StackMiddleware\PageCache->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#37 /app/web/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(48): Asm89\Stack\Cors->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#38 /app/web/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(51): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#39 /app/web/core/lib/Drupal/Core/StackMiddleware/AjaxPageState.php(36): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#40 /app/web/core/lib/Drupal/Core/StackMiddleware/StackedHttpKernel.php(51): Drupal\Core\StackMiddleware\AjaxPageState->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#41 /app/web/core/lib/Drupal/Core/DrupalKernel.php(741): Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#42 /app/web/index.php(19): Drupal\Core\DrupalKernel->handle(Object(Symfony\Component\HttpFoundation\Request))
#43 {main}

Steps to reproduce

1. Go to some entities' field list (for Nodes: /admin/structure/types/manage/[node_type]/fields)
2. Click on button above to add new field
3. Go thru all steps of new field configuration, end on Field settings edit form (/admin/structure/types/manage/[node_type]/add-field/node/[new_field_id], for example)
4. Try to save new field by clicking Submit after filling in the form

Proposed resolution

I don't have enough time to properly test and understand what happening and how it need to be solved correctly, but I was able to avoid described error with just checking value to be added as third-party setting within required_by_form_mode_field_config_edit_form_builder().
See patch I will attach for solution that helped me.

Also I'll set priority to Critical as this bug breaks one of core functionalities.