Component triggers assert when adding array prop to an in use component
>>> [!note] Migrated issue
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<!-- Migrated from issue #3579365. -->
Reported by: [lauriii](https://www.drupal.org/user/1078742)
Related to !756
>>>
<h3 id="overview">Overview</h3>
<p>When a component’s schema is changed (e.g. a new array-type prop is added) and there's existing content that already uses that component, an assertion <code>assert($this->cardinality === 1)</code> from <code>StorablePropShape::__construct()</code> fails.</p>
<p><b>Steps to reproduce</b></p>
<ol>
<li>Create a page that uses the 'All Props' component.</li>
<li>Add a new array-type prop to the component’s schema (e.g. <code>type: array</code>, <code>items: { type: string }</code>).</li>
<li>Clear cache and refresh the page.</li>
</ol>
<h3 id="proposed-resolution">Proposed resolution</h3>
<p>Fix the component upgrade when adding array props.</p>
<h3 id="ui-changes">User interface changes</h3>
issue