**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
```
{
    if (query.replica.empty())
        throw Exception("Replica name is empty", ErrorCodes::BAD_ARGUMENTS);
    if (!table_id.empty())
    {
        getContext()->checkAccess(AccessType::SYSTEM_DROP_REPLICA, table_id);
        StoragePtr table = DatabaseCatalog::instance().getTable(table_id, getContext());
        if (!dropReplicaImpl(query, table))
            throw Exception("Table " + table_id.getNameForLogs() + " is not replicated", ErrorCodes::BAD_ARGUMENTS);
    }
    else if (!query.database.empty())
    {
        getContext()->checkAccess(AccessType::SYSTEM_DROP_REPLICA, query.database);
        DatabasePtr database = DatabaseCatalog::instance().getDatabase(query.database);
        for (auto iterator = database->getTablesIterator(getContext()); iterator->isValid(); iterator->next())
            dropReplicaImpl(query, iterator->table());
        LOG_TRACE(log, "Dropped replica {} from database {}", query.replica, backQuoteIfNeed(database->getDatabaseName()));
    }
    else if (query.is_drop_whole_replica)
    {
        getContext()->checkAccess(AccessType::SYSTEM_DROP_REPLICA);
        auto databases = DatabaseCatalog::instance().getDatabases();
        for (auto & elem : databases)
        {
            DatabasePtr & database = elem.second;
            for (auto iterator = database->getTablesIterator(getContext()); iterator->isValid(); iterator->next())
                dropReplicaImpl(query, iterator->table());
            LOG_TRACE(log, "Dropped replica {} from database {}", query.replica, backQuoteIfNeed(database->getDatabaseName()));
        }
    }