**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
```
column.type = name_type_it->type;
            else
                column.type = defaults_sample_block.getByName(column.name).type;
            column.default_desc.kind = columnDefaultKindFromString(col_decl.default_specifier);
            column.default_desc.expression = default_expr;
        }
        else if (col_decl.type)
            column.type = name_type_it->type;
        else
            throw Exception();
        if (col_decl.comment)
            column.comment = col_decl.comment->as<ASTLiteral &>().value.get<String>();
        if (col_decl.codec)
        {
            if (col_decl.default_specifier == "ALIAS")
                throw Exception{"Cannot specify codec for column type ALIAS", ErrorCodes::BAD_ARGUMENTS};
            column.codec = CompressionCodecFactory::instance().validateCodecAndGetPreprocessedAST(
                col_decl.codec, column.type, sanity_check_compression_codecs);
        }
        if (col_decl.ttl)
            column.ttl = col_decl.ttl;
        res.add(std::move(column));
    }
    if (context_->getSettingsRef().flatten_nested)
        res.flattenNested();
    if (res.getAllPhysical().empty())
        throw Exception{"Cannot CREATE table without physical columns", ErrorCodes::EMPTY_LIST_OF_COLUMNS_PASSED};
    return res;
}
ConstraintsDescription InterpreterCreateQuery::getConstraintsDescription(const ASTExpressionList * constraints)