🧭 fix: Robust 404 Conversation Not Found Redirect (#11853)

* fix: route to new conversation when conversation not found

* Addressed PR feedback

* fix: Robust 404 conversation redirect handling

- Extract `isNotFoundError` utility to `utils/errors.ts` so axios stays
  contained in one place rather than leaking into route/query layers
- Add `initialConvoQuery.isError` to the useEffect dependency array so
  the redirect actually fires when the 404 response arrives after other
  deps have already settled (was the root cause of the blank screen)
- Show a warning toast so users understand why they were redirected
- Add `com_ui_conversation_not_found` i18n key

* fix: Enhance error handling in getResponseStatus function

- Update the getResponseStatus function to ensure it correctly returns the status from error objects only if the status is a number. This improves robustness in error handling by preventing potential type issues.

* fix: Improve conversation not found handling in ChatRoute

- Enhance error handling when a conversation is not found by checking additional conditions before showing a warning toast.
- Update the newConversation function to include model data and preset options, improving user experience during error scenarios.

* fix: Log error details for conversation not found in ChatRoute

- Added logging for the initial conversation query error when a conversation is not found, improving debugging capabilities and error tracking in the ChatRoute component.

---------

Co-authored-by: Dan Lew <daniel@mightyacorn.com>

client/src/utils/errors.ts

@@ -0,0 +1,21 @@
+import axios from 'axios';
+
+/**
+ * Returns the HTTP response status code from an error, regardless of the
+ * HTTP client used.  Handles Axios errors first, then falls back to checking
+ * for a plain `status` property so callers never need to import axios.
+ */
+export const getResponseStatus = (error: unknown): number | undefined => {
+  if (axios.isAxiosError(error)) {
+    return error.response?.status;
+  }
+  if (error != null && typeof error === 'object' && 'status' in error) {
+    const { status } = error as { status: unknown };
+    if (typeof status === 'number') {
+      return status;
+    }
+  }
+  return undefined;
+};
+
+export const isNotFoundError = (error: unknown): boolean => getResponseStatus(error) === 404;

client/src/utils/index.ts

@@ -3,6 +3,7 @@ import type { UIActionResult } from '@mcp-ui/client';
 import { TAskFunction } from '~/common';
 import logger from './logger';
 
+export * from './errors';
 export * from './map';
 export * from './json';
 export * from './files';