PHP 8.5 deprecations

Problem/Motivation

Getting

Deprecated function: Using null as an array offset is deprecated, use an empty string instead in shs_term_load_all_parents() (line 95 of modules/contrib/shs/shs.module).
shs_term_load_all_parents() (Line: 91)
Drupal\shs\WidgetDefaults->getParentDefaults() (Line: 208)
Drupal\shs\Plugin\Field\FieldWidget\OptionsShsWidget->formElement() (Line: 116)
Drupal\shs_chosen\Plugin\Field\FieldWidget\OptionsShsChosenWidget->formElement() (Line: 464)
Drupal\Core\Field\WidgetBase->formSingleElement() (Line: 101)
Drupal\Core\Field\WidgetBase->form() (Line: 197)
Drupal\Core\Entity\Entity\EntityFormDisplay->buildForm() (Line: 121)
Drupal\Core\Entity\ContentEntityForm->form() (Line: 140)
Drupal\node\Form\NodeForm->form() (Line: 108)
Drupal\Core\Entity\EntityForm->buildForm()
call_user_func_array() (Line: 554)
Drupal\Core\Form\FormBuilder->retrieveForm() (Line: 303)
Drupal\Core\Form\FormBuilder->buildForm() (Line: 73)
Drupal\Core\Controller\FormController->getContentResult()
call_user_func_array() (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->{closure:Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber::wrapControllerExecutionInRenderContext():121}() (Line: 634)
Drupal\Core\Render\Renderer::{closure:Drupal\Core\Render\Renderer::executeInRenderContext():634}()
Fiber->resume() (Line: 649)
Drupal\Core\Render\Renderer->executeInRenderContext() (Line: 121)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext() (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->{closure:Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber::onController():96}() (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: 118)
Drupal\page_cache\StackMiddleware\PageCache->pass() (Line: 92)
Drupal\page_cache\StackMiddleware\PageCache->handle() (Line: 53)
Asm89\Stack\Cors->handle() (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle() (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle() (Line: 53)
Drupal\Core\StackMiddleware\AjaxPageState->handle() (Line: 54)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle() (Line: 745)
Drupal\Core\DrupalKernel->handle() (Line: 19)

Screenshot is also attached

Steps to reproduce

1. Upgrade to PHP 8.5
2. Visit a content edit page that uses shs

Proposed resolution

Fix code for PHP 8.5

Remaining tasks

MR and Patch

User interface changes

None

API changes

None

Data model changes

None