[Bug]: [null & default] bulk writer does not support "None" data

[binbinlv]

Is there an existing issue for this?

• [X] I have searched the existing issues

Environment

- Milvus version:
- Deployment mode(standalone or cluster):
- MQ type(rocksmq, pulsar or kafka):    
- SDK version(e.g. pymilvus v2.0.0rc2):
- OS(Ubuntu or CentOS): 
- CPU/Memory: 
- GPU: 
- Others:

Current Behavior

bulk writer does not support "None" data

pymilvus.exceptions.MilvusException: <MilvusException: (code=1, message=Illegal scalar value for field 'int_scalar', value overflow or type mismatch)>

Expected Behavior

bulk writer supports "None" data

Steps To Reproduce

NA

Milvus Log

No response

Anything else?

No response

[smellthemoon]

by design.