[Search:AppSearch:Engines:Documents page]Issues with Add new documents flyout when getting errors

[L1nBra]

Description When flyout gets errors, they should be announced to the user and focus should be on the field which is in error.

Preconditions Stateful App Search -> Engines -> Documents page is opened. Engine is added. Use Screen Reader (NVDA).

Steps to reproduce

1.Using only keyboard navigate to Index documents button by pressing Tab key. 2.Press Enter. 3.Navigate to Paste or upload Json button. 4.Press Enter. 5.Upload incorrect file (f.e.: PNG file). 6.Navigate to Continue button. 7.Press Enter. 8.Observe flyout and screen reader.

Screen recording https://github.com/user-attachments/assets/acfc1747-c55b-4305-9f13-be4515e2421d

UI elements + NVDA Speech Viewer

Actual Result

• Button behind flyout is announced ("button Index documents"), error is not announced by screen reader, navigation continues from next element (top left of the page). Same behavior on Paste tab (after Paste or upload Json button) when pasting incorrect JSON.

Expected Result

• Button behind flyout is not announced, error is announced to the user, focus is on element which is in error (in this case on the uploaded file button).

Meta Issue

Kibana Version: 8.17.0-SNAPSHOT

OS: Windows 11 Pro

Browser: Chrome Version 130.0.6723.70 (Official Build) (64-bit)

Screen reader: NVDA

WCAG or Vendor Guidance (optional)

• Understanding SC 3.3.1: Error Identification (Level A)(https://www.w3.org/WAI/WCAG22/Understanding/error-identification.html)
• Understanding SC 2.4.3: Focus Order (Level A)(https://www.w3.org/WAI/WCAG22/Understanding/focus-order.html)

Related to: https://github.com/elastic/search-team/issues/8256

[elasticmachine]

Pinging @elastic/kibana-accessibility (Project:Accessibility)