**How to reproduce**
Clickhouse version 21.5

```
cat /etc/clickhouse-server/users.xml
<?xml version="1.0"?>
<yandex>
    <!-- Profiles of settings. -->
    <profiles>
        <!-- Default settings. -->
        <default>
            <data_type_default_nullable>1</data_type_default_nullable>
            <load_balancing>random</load_balancing>
        </default>
....

2021.04.04 01:23:42.453678 [ 29048 ] {} <Error> Application: DB::Exception: Nested type Array(UInt64) cannot be inside Nullable type: Cannot attach table `system`.`crash_log` from metadata file /var/lib/clickhouse/metadata/system/crash_log.sql from query ATTACH TABLE system.crash_log (`event_date` Date, `event_time` DateTime, `timestamp_ns` UInt64, `signal` Int32, `thread_id` UInt64, `query_id` String, `trace` Array(UInt64), `trace_full` Array(String), `version` String, `revision` UInt32, `build_id` String) ENGINE = MergeTree ORDER BY (event_date, event_time) SETTINGS index_granularity = 8192: while loading database `system` from path /var/lib/clickhouse/metadata/system
```
const InterpreterCreateQuery::TableProperties & properties)
{
    std::unique_ptr<DDLGuard> guard;
    String data_path;
    DatabasePtr database;
    bool need_add_to_database = !create.temporary;
    if (need_add_to_database)
    {
        /** If the request specifies IF NOT EXISTS, we allow concurrent CREATE queries (which do nothing).
          * If table doesn't exist, one thread is creating table, while others wait in DDLGuard.
          */
        guard = DatabaseCatalog::instance().getDDLGuard(create.database, create.table);
        database = DatabaseCatalog::instance().getDatabase(create.database);
        assertOrSetUUID(create, database);
        
        if (database->isTableExist(create.table, getContext()))
        {
            
            if (create.if_not_exists)