Using item_list in examples break rendering

Problem/Motivation

As for UI patterns (Issue #3529153 → ) since v1.0.2, we have error on example pages using theme: item_list

Error in the navigator :

Le site Web a rencontré une erreur inattendue.

Twig\Error\RuntimeError: An exception has been thrown during the rendering of a template (""type" is an invalid render array key. Value should be an array but got a string.") in "customer:layout" at line 11. in Twig\Template->yield() (line 11 of themes/custom/customer/components/layout/layout.twig).

template_preprocess_item_list()
call_user_func_array() (Line: 261)
Drupal\Core\Theme\ThemeManager->render() (Line: 491)
Drupal\Core\Render\Renderer->doRender() (Line: 504)
Drupal\Core\Render\Renderer->doRender() (Line: 248)
Drupal\Core\Render\Renderer->render() (Line: 484)
Drupal\Core\Template\TwigExtension->escapeFilter() (Line: 77)
__TwigTemplate_ea68831567b6bbe1d179b4905979d5a4->doDisplay() (Line: 402)
Twig\Template->yield() (Line: 141)
__TwigTemplate_03c9ed99ec99034085d3fa3357192c92___2130353984->doDisplay() (Line: 402)
Twig\Template->yield() (Line: 44)
__TwigTemplate_03c9ed99ec99034085d3fa3357192c92->doDisplay() (Line: 402)
Twig\Template->yield() (Line: 358)
Twig\Template->display() (Line: 373)
Twig\Template->render() (Line: 51)
Twig\TemplateWrapper->render() (Line: 234)
Drupal\Core\Template\TwigEnvironment->renderInline() (Line: 54)
Drupal\Core\Render\Element\InlineTemplate::preRenderInlineTemplate()
call_user_func_array() (Line: 113)
Drupal\Core\Render\Renderer->doTrustedCallback() (Line: 875)
Drupal\Core\Render\Renderer->doCallback() (Line: 432)
Drupal\Core\Render\Renderer->doRender() (Line: 504)
Drupal\Core\Render\Renderer->doRender() (Line: 504)
Drupal\Core\Render\Renderer->doRender() (Line: 248)
Drupal\Core\Render\Renderer->render() (Line: 238)
Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}() (Line: 638)
Drupal\Core\Render\Renderer->executeInRenderContext() (Line: 231)
Drupal\Core\Render\MainContent\HtmlRenderer->prepare() (Line: 128)
Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse() (Line: 90)
Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray()
call_user_func() (Line: 111)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch() (Line: 186)
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: 116)
Drupal\page_cache\StackMiddleware\PageCache->pass() (Line: 90)
Drupal\page_cache\StackMiddleware\PageCache->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: 741)

Steps to reproduce

1. Use theme: item_list in an example
   Example :

   id: 'page-list-example'
   category: list
   enabled: true
   label: 'List example'
   render:
     - theme: item_list
       list_type: ul
       items:
         - type: html_tag
           tag: p
           value: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ...'
         - type: html_tag
           tag: p
           value: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ...'
         - type: html_tag
           tag: p
           value: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ...'
       

2. Open your example page in navigator

Proposed resolution

This bug also concerns UI Patterns v2.0.4

Our temporary solution is to prefix items content with #

For example :

- type: html_tag
  tag: p
  value: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ...'

became :

- '#type': html_tag
  '#tag': p
  '#value': 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ...'

Is there a better solution ?

Thanks in advance for your help and feedback