fix: Resolve issue with wrong error message serialization for cognify… (#1413)

… pipeline in backend

<!-- .github/pull_request_template.md -->

## Description
Resolve issue with cognify backend error message serialization

## Type of Change
<!-- Please check the relevant option -->
- [x ] Bug fix (non-breaking change that fixes an issue)
- [ ] New feature (non-breaking change that adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update
- [ ] Code refactoring
- [ ] Performance improvement
- [ ] Other (please specify):

## Testing
Reproduced error it is handled appropriately 

## Pre-submission Checklist
<!-- Please check all boxes that apply before submitting your PR -->
- [ x] **I have tested my changes thoroughly before submitting this PR**
- [ x] **This PR contains minimal changes necessary to address the
issue/feature**
- [ x] My code follows the project's coding standards and style
guidelines
- [ x] I have added tests that prove my fix is effective or that my
feature works
- [ x] I have added necessary documentation (if applicable)
- [ x] All new and existing tests pass
- [ x] I have searched existing PRs to ensure this change hasn't been
submitted already
- [x ] I have linked any relevant issues in the description
- [ x] My commits have clear and descriptive messages

## DCO Affirmation
I affirm that all code in every commit of this pull request conforms to
the terms of the Topoteretes Developer Certificate of Origin.

cognee/api/v1/cognify/routers/get_cognify_router.py

@@ -3,6 +3,7 @@ import asyncio
 from uuid import UUID
 from pydantic import Field
 from typing import List, Optional
+from fastapi.encoders import jsonable_encoder
 from fastapi.responses import JSONResponse
 from fastapi import APIRouter, WebSocket, Depends, WebSocketDisconnect
 from starlette.status import WS_1000_NORMAL_CLOSURE, WS_1008_POLICY_VIOLATION
@@ -119,7 +120,7 @@ def get_cognify_router() -> APIRouter:
 
             # If any cognify run errored return JSONResponse with proper error status code
             if any(isinstance(v, PipelineRunErrored) for v in cognify_run.values()):
-                return JSONResponse(status_code=420, content=cognify_run)
+                return JSONResponse(status_code=420, content=jsonable_encoder(cognify_run))
             return cognify_run
         except Exception as error:
             return JSONResponse(status_code=409, content={"error": str(error)})