[Bug][parquet] Read struct(null, null) should return struct(null, null) instead of null

[Zouxxyy]

Search before asking

• I searched in the issues and found nothing similar.

Minimal reproduce step

CREATE TABLE t (i INT, s STRUCT<f1: INT, f2: INT>);
INSERT INTO t VALUES (1, STRUCT(null, null));
SELECT * FROM t;

should return [null, null] instead of null

Are you willing to submit a PR?

• I'm willing to submit a PR!