Invalid null handling in mongo collections

[universalmind303]

Steps to reproduce

mongo shell

test> db.createCollection("nulls_test")
{ ok: 1 }
test> db.nulls_test.insertMany([{ value: 1}, {value: null}])

glaredb

> SELECT * FROM read_mongodb('mongodb://localhost:27017/test', 'test', 'nulls_test');
Error: External error: External error: Unhandled element type to arrow type conversion; Null, Int32

Expected

┌─────────────────┐
│ value           │
│              ── │
│           Int32 │
╞═════════════════╡
│               1 │
│            NULL │
└─────────────────┘