Deprecated function: simplexml_load_string()

Problem/Motivation

When saving the Icons vocabulary I get the following PHP error

Deprecated function: simplexml_load_string(): Passing null to parameter #1 ($data) of type string is deprecated in function Drupal\icon_select\Helper\SvgSpriteGenerator::generateSprites() (line 49 in file /var/www/html/web/modules/contrib/icon_select/src/Helper/SvgSpriteGenerator.php). =>

array:27 [▼
  "26: simplexml_load_string()" => array:1 [▶]
  "25: Drupal\icon_select\Helper\SvgSpriteGenerator::generateSprites()" => array:2 [▶]
  "24: icon_select_vocabulary_form_submit()" => array:2 [▶]
  "23: call_user_func_array()" => array:1 [▶]
  "22: Drupal\Core\Form\FormSubmitter->executeSubmitHandlers()" => array:2 [▶]
  "21: Drupal\Core\Form\FormSubmitter->doSubmitForm()" => array:2 [▶]
  "20: Drupal\Core\Form\FormBuilder->processForm()" => array:2 [▶]
  "19: Drupal\Core\Form\FormBuilder->buildForm()" => array:2 [▶]
  "18: Drupal\Core\Controller\FormController->getContentResult()" => array:2 [▶]
  "17: call_user_func_array()" => array:1 [▶]
  "16: Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()" => array:1 [▶]
  "15: Drupal\Core\Render\Renderer->executeInRenderContext()" => array:2 [▶]
  "14: Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext()" => array:2 [▶]
  "13: Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()" => array:1 [▶]
  "12: Symfony\Component\HttpKernel\HttpKernel->handleRaw()" => array:2 [▶]
  "11: Symfony\Component\HttpKernel\HttpKernel->handle()" => array:2 [▶]
  "10: Drupal\Core\StackMiddleware\Session->handle()" => array:2 [▶]
  "\u{A0}9: Drupal\Core\StackMiddleware\KernelPreHandle->handle()" => array:2 [▶]
  "\u{A0}8: Drupal\Core\StackMiddleware\ContentLength->handle()" => array:2 [▶]
  "\u{A0}7: Drupal\page_cache\StackMiddleware\PageCache->pass()" => array:2 [▶]
  "\u{A0}6: Drupal\page_cache\StackMiddleware\PageCache->handle()" => array:2 [▶]
  "\u{A0}5: Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle()" => array:2 [▶]
  "\u{A0}4: Drupal\Core\StackMiddleware\NegotiationMiddleware->handle()" => array:2 [▶]
  "\u{A0}3: Drupal\Core\StackMiddleware\AjaxPageState->handle()" => array:2 [▶]
  "\u{A0}2: Drupal\Core\StackMiddleware\StackedHttpKernel->handle()" => array:2 [▶]
  "\u{A0}1: Drupal\Core\DrupalKernel->handle()" => array:2 [▶]
  "\u{A0}0: main()" => array:2 [▶]

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes