ui5-list: `tagName` TypeError when a ui5-li-custom item isn't rendered yet during list render

[Lukas742]

Bug Description

Since 2.26.0, a ui5-list containing ui5-li-custom items can throw during render ending up without height.

You can see that here in our Storybook, the MessageView renders a list with custom list items: https://ui5.github.io/webcomponents-react/v2/iframe.html?id=user-feedback-messageview--default&viewMode=story

So without a patch, the MessageView component is not usable with v2.26.0 of ui5wc/r.

AI generated analysis:

While the list renders, ariaDescriptionText → _hasInteractiveItems iterates the items and calls _hasFocusableElements() on each custom item → _getFocusableElements() → getTabbableElements(this.getFocusDomRef()). If an item hasn't finished its first render, getFocusDomRef() returns undefined, and getTabbableElements dereferences it (el.tagName) with no null-check, throwing and aborting the list render.

Affected Component

ui5-list, ui5-li-custom

Expected Behaviour

The list should render without throwing when a custom item's DOM ref isn't ready yet — getTabbableElements(undefined) should return [] (or the callers should skip items without a focus DOM ref).

Isolated Example

https://stackblitz.com/edit/github-7gvnntpw?file=index.html,main.js

Steps to Reproduce

1. Open the isolated example.
2. On load, an Uncaught TypeError: Cannot read properties of undefined (reading 'tagName') is thrown (deterministic; getFocusDomRef() logs undefined).

In a real app / production build the same throw happens inside the list's own render, so the list (and components built on it) render blank.

Log Output, Stack Trace or Screenshots

TypeError: Cannot read properties of undefined (reading 'tagName')
    at getTabbableElements
    at ListItemCustom._getFocusableElements
    at ListItemCustom._hasFocusableElements
    at get _hasInteractiveItems   // Array.some over getItems()
    at get ariaDescriptionText
    at <list render>

Priority

High

UI5 Web Components Version

2.26.0

Browser

Chrome, Edge, Firefox, Safari

Operating System

No response

Additional Context

No response

Organization

UI5WCR

Declaration

• I’m not disclosing any internal or sensitive information.