[Bug]: NPE in local_collection.py when invoke find method

[shoocstorm]

Bug Description

Hi Team,
Appreciate if you could take a look below NPE.

It seems it could return empty cands_list and subsquently results in NPE in cand.fields in local_collection.py.

293 cands_list = self.store_mgr.fetch_cands_data(label_list) 294 cands_fields = [json.loads(cand.fields) for cand in cands_list]

Best Regards

Steps to Reproduce

invoke the find method of ov client

Expected Behavior

No NPE

Actual Behavior

NPE thrown

Minimal Reproducible Example

Error Logs

[0] [2026-02-14 15:49:44.119 +0000] DEBUG (Javis-Logger): [agent:Javis] start - Retrieving context | user=Master | conv=Bot-UI-CONV-2026-02-14T15-49-28-978Z | exec=bfa30cb4-5a37-4346-aad1-983ed9087105
[0]     agentId: "JavisBot"
[0]     modelName: "dynamic"
[0]     operationId: "bfa30cb4-5a37-4346-aad1-983ed9087105"
[0]     userId: "Master"
[0]     conversationId: "Bot-UI-CONV-2026-02-14T15-49-28-978Z"
[0]     executionId: "bfa30cb4-5a37-4346-aad1-983ed9087105"
[0]     operation: "retriever"
[0]     retrieverId: "openviking_search"
[0]     event: "retriever.search.started"
[0]     input: "What is FSA account?"
[0] [2026-02-14 15:49:44.119 +0000] DEBUG (Javis-Logger): [RAG QUERY] Starting retrieval for query: "What is FSA account?" in viking://resources/README.md
[0] [2026-02-14 15:49:44.746 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE] 2026-02-14 23:49:44,745 - httpx - INFO - HTTP Request: POST http://127.0.0.1:1234/v1/embeddings "HTTP/1.1 200 OK"
[0] [2026-02-14 15:49:44.750 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE] 2026-02-14 23:49:44,750 - openviking.storage.viking_vector_index_backend - ERROR - Error searching collection 'context': 'NoneType' object has no attribute 'fields'
[0] [2026-02-14 15:49:44.750 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE] Traceback (most recent call last):
[0] [2026-02-14 15:49:44.751 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE]   File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/site-packages/openviking/utils/async_utils.py", line 27, in run_async
[0] [2026-02-14 15:49:44.751 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE]     loop = asyncio.get_running_loop()
[0] [2026-02-14 15:49:44.751 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE]            ^^^^^^^^^^^^^^^^^^^^^^^^^^
[0] [2026-02-14 15:49:44.751 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE] RuntimeError: no running event loop
[0] [2026-02-14 15:49:44.751 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE] During handling of the above exception, another exception occurred:
[0] [2026-02-14 15:49:44.751 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE] Traceback (most recent call last):
[0] [2026-02-14 15:49:44.751 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE]   File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/site-packages/openviking/storage/viking_vector_index_backend.py", line 654, in search
[0] [2026-02-14 15:49:44.751 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE]     result = coll.search_by_vector(
[0] [2026-02-14 15:49:44.751 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE]              ^^^^^^^^^^^^^^^^^^^^^^
[0] [2026-02-14 15:49:44.751 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE]   File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/site-packages/openviking/storage/vectordb/collection/collection.py", line 327, in search_by_vector
[0] [2026-02-14 15:49:44.751 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE]     return self.__collection.search_by_vector(
[0] [2026-02-14 15:49:44.751 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE]            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[0] [2026-02-14 15:49:44.752 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE]   File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/site-packages/openviking/storage/vectordb/collection/local_collection.py", line 294, in search_by_vector
[0] [2026-02-14 15:49:44.752 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE]     cands_fields = [json.loads(cand.fields) for cand in cands_list]
[0] [2026-02-14 15:49:44.752 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE]                                ^^^^^^^^^^^
[0] [2026-02-14 15:49:44.752 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE] AttributeError: 'NoneType' object has no attribute 'fields'
[0] [2026-02-14 15:49:44.752 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE] 2026-02-14 23:49:44,752 - openviking.storage.viking_vector_index_backend - ERROR - Error searching collection 'context': 'NoneType' object has no attribute 'fields'
[0] [2026-02-14 15:49:44.753 +0000] DEBUG (Javis-Logger): [PYTHON BRIDGE] Traceback (most recent call last):

OpenViking Version

0.1.12

Python Version

3.12.9

Operating System

macOS

Model Backend

Other

Additional Context

No response

[MaojiaSheng]

@kkkwjx07