bug(ui): invalid URL in description embed-link form crashes the editor ("Invalid slot 'errorMessage'")

[harsh-vador]

Description

In the rich-text Description editor, opening the image/link embed popover and entering an invalid URL crashes the whole editor with the app error boundary:

Something went wrong
Invalid slot "errorMessage". Valid slot names are "description".

The user is dropped out of the description edit entirely.

Steps to reproduce

1. Open any entity → Edit Description.
2. In the toolbar, click the image / embed button → the popover opens (Link / Upload tabs).
3. On the Link tab, type an invalid URL (e.g. ttt).
4. 💥 The editor unmounts and shows "Something went wrong — Invalid slot 'errorMessage'. Valid slot names are 'description'."

Expected

The field shows an inline "Invalid URL" validation message and the editor keeps working (this is the behaviour on the current production release).

Actual

React-aria throws an invalid-slot error, the error boundary catches it, and the editor is replaced by the "Something went wrong" page.

Root cause

openmetadata-ui/.../components/BlockEditor/Extensions/image/EmbedLinkElement/EmbedLinkElement.tsx renders the URL validation error as a standalone HintText next to the Input:

<Input isInvalid={fieldState.invalid} ... />
{fieldState.error && (
  <HintText isInvalid>{fieldState.error.message}</HintText>   // <-- crashes
)}

HintText isInvalid resolves to react-aria slot="errorMessage", but it sits inside a TextField/Input context that only registers the description slot → react-aria throws Invalid slot "errorMessage". Valid slot names are "description".

When it was introduced

Introduced on main by #29964 (commit 2cd612fe9ff, 2026-07-13, "refactor(context-center): wrap header components with HeaderShell") — it added EmbedLinkElement.tsx in its current Input + standalone-HintText form. It is the only commit in that file's history.

Current production works because the deployed UI release predates #29964. This regression is on main and will ship in the next release unless fixed.

Suggested fix

Surface the validation error through the field's own error mechanism (the correct slot) rather than a sibling <HintText> — e.g. pass the error via the Input/TextField error prop, or render the message outside the TextField slot context so it isn't captured as slot="errorMessage".

Environment

• Area: UI — BlockEditor / description embed-link popover
• Frontend only (reproduces regardless of backend; observed pointing at prod backend)
• Browser: Chrome