[fix] complex type npe problem

[gnehil]

Proposed changes

Issue Number: close #xxx

Problem Summary:

Fixed the following issues:

1. writing map and struct type field npe when then field is null
2. reading map type field npe when key or value is null

Checklist(Required)

1. Does it affect the original behavior: (Yes/No/I Don't know)
2. Has unit tests been added: (Yes/No/No Need)
3. Has document been added or modified: (Yes/No/No Need)
4. Does it need to update dependencies: (Yes/No)
5. Are there any changes that cannot be rolled back: (Yes/No)

Further comments

If this is a relatively large or complex change, kick off the discussion at dev@doris.apache.org by explaining why you chose the solution you did and what alternatives you considered, etc...