[Bug] PDF Embed API crashes on PDFs with annotations after 09/03/2026 update — TypeError in QuickToolItem

Hi everyone,

Since the 09/03/2026 update, the Adobe PDF Embed API has been failing to render PDFs that contain annotations. This was working perfectly before the update.

Environment:
- PDF Embed API (dc-core 4.7.7, dcpreviewdropin 4.2.0_2.1400.0, dc-comments-dropin 4.13.0_2.1414.0)
- Issue occurs across browsers (tested Chrome and Firefox)
- Only affects PDFs with annotations; PDFs without annotations load fine

What happens:
The PDF begins to load and is briefly visible, then disappears almost immediately. The viewer container remains but the document content is gone.

Console error:

TypeError: can't access property "icon", r[I] is undefined
    QuickToolItem https://documentcloud.adobe.com/dcpreviewdropin/4.2.0_2.1400.0/bootstrap.js:2

The full stack trace shows the error originates in QuickToolItem within the preview dropin, triggered during the commenting/annotation initialization flow:

1. The PDF starts rendering via _startRenderingPDF → _preloadPageAtLowRes
2. The comments dropin initializes via initializeAction → initializeActionUtil
3. populateQTVerbGroup is called recursively (6 times in the trace)
4. It hits QuickToolItem, which tries to access the "icon" property on an undefined toolbar item (r[I] is undefined)
5. The unhandled TypeError causes the entire viewer to fail

This looks like a regression where the toolbar/verb configuration was updated but one or more annotation tool entries are now missing or undefined in the registry, so when QuickToolItem iterates over them, it hits an undefined entry and crashes.

Has anyone else encountered this since the latest update? Any known workarounds?

Thanks for any help.