fix(web): auto-hide error banner when chat error is cleared

The error banner visibility was only set to true when an error occurred,
but was never automatically hidden when the error state was cleared. This
caused stale 'Network error' banners to persist even after a new request
started successfully.

Now the banner visibility is properly synchronized with the error state:
- When error is truthy: banner is visible
- When error is falsy: banner is hidden

This ensures that benign transient errors that get cleared by the AI SDK
(e.g. when a new request starts) no longer leave lingering error banners.

Fixes SOU-2018

Co-authored-by: Michael Sukkarieh <msukkari@users.noreply.github.com>

Author: cursoragent

packages/web/src/ee/features/chat/components/chatThread/chatThread.tsx

@@ -420,11 +420,11 @@ export const ChatThread = ({
     }, [scrollRef]);
 
 
-    // Keep the error state & banner visibility in sync.
+    // Keep the error state & banner visibility in sync. The banner should
+    // automatically hide when the error is cleared (e.g. when a new request
+    // starts successfully), preventing stale error banners from lingering.
     useEffect(() => {
-        if (error) {
-            setIsErrorBannerVisible(true);
-        }
+        setIsErrorBannerVisible(!!error);
     }, [error]);
 
     const onSubmit = useCallback(async (children: Descendant[], editor: CustomEditor, attachments: AttachmentData[]) => {