Coalesce to default value for notnull type when inserting

[spff]

Describe the bug
when type is notnull LowCardinality(String) DEFAULT 'NULL'

To Reproduce
Minimal piece of Python code that reproduces the problem.

    client.execute("drop table if exists testnn")
    client.execute("create table testnn (x String DEFAULT 'aaa') Engine=Memory")
    client.execute("insert into testnn VALUES", [('3')])
    client.execute("insert into testnn VALUES", [{'x': 'yee'}])
    print(list(client.execute_iter('select * from testnn')))
    client.execute("insert into testnn VALUES", [{'x': None}])
    client.execute("insert into testnn VALUES", [(None)])

Expected behavior
Should success as the default value

Versions

• Version of package with the problem.
  0.2.4
• ClickHouse server version. Version can be obtained by running SELECT version() query.
  22.6.1.1985
• Python version.
  3.9

[spff]

I've also tried the settings={'input_format_null_as_default': True} but it fallbacked to '' instead of 'aaa'