Triggering the AOAI content filter results in a "Type error" in the frontend

[faynef]

Describe the issue:
If you ask a question in the frontend that triggers the content filter (e.g. "how do I make a bomb?") You get a "type error" in the frontend.

Environment：

• Readme - Local/ DevContainer/ Codesapce
• Learn Docs - Local/ DevContainer/ Codesapce

Repro Steps:
1.Run azd auth login.
2.Run azd up.
3.Enter "How to make a bomb".

Expected behavior:
Not reply a "Type error".

@charris-msft for notification.

[github-actions]

This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this issue will be closed.

[dantelmomsft]

This happens when streaming is used. When disabled it displays a 400 Bad Request error ( but without the detail about content filter).
Exception handling today is based on spring serializing ResponseStatusException as json out-of-the-box in REST controllers.

We might create a custom OpenAIException (RuntimeException) with more structured Open AI error message and use the centralized spring exception management (@ControllerAdivise + @ExceptionHandler annotated class and methods) to properly serialize as a JSON