TYPO3 Core

There are some minor errors in the html-structure of the Lit Element tree (Pagetree, Categorytree etc.) which can be improved.

I used https://validator.w3.org/nu/#textarea and copied the rendered HTML from the TYPO3 backend into it:

Error: Bad value for attribute aria-owns on element div: An IDREFS value must contain at least one non-whitespace character.¶

<div role="treeitem" … class="node" … aria-owns="" …>

Error: Bad value for attribute aria-expanded on element div.¶

<div role="treeitem" … class="node" … aria-expanded="" …>

Error: Bad value 0 for attribute aria-level on element div: Zero is not a positive integer.¶

<div role="treeitem" … class="node" title="uid=0 Category" aria-level="0" … data-id="0" data-tree-id="0" …>↩

Error: Element div not allowed as child of element span in this context. (Suppressing further errors from this subtree.)¶

<div class="node-treeline node-treeline--last" data-origin="0"></div>

<div class="node-contentlabel">    

Contexts in which element div may be used:
Where flow content is expected.
As a child of a dl element.

Content model for element span:
Phrasing content.