**How to reproduce**
Clickhouse version 21.2-21.3

```
SELECT x
FROM
(
    SELECT 1 AS x
    UNION DISTINCT
    SELECT 1
)
LIMIT 1

Query id: b82bbb8d-dea9-4f1c-9a2f-5b0e9b6c2422


0 rows in set. Elapsed: 0.002 sec.

Received exception from server (version 21.2.3):
Code: 49. DB::Exception: Received from localhost:9000. DB::Exception: Bad cast from type DB::ASTSelectWithUnionQuery to DB::ASTSelectQuery.
```


, metadata_snapshot(metadata_snapshot_)
{
    checkStackSize();
    initSettings();
    const Settings & settings = context->getSettingsRef();
    if (settings.max_subquery_depth && options.subquery_depth > settings.max_subquery_depth)
        throw Exception("Too deep subqueries. Maximum: " + settings.max_subquery_depth.toString(),
            ErrorCodes::TOO_DEEP_SUBQUERIES);
    bool has_input = input || input_pipe;
    if (input)
    {
        
        source_header = input->getHeader();
    }
    else if (input_pipe)
    {
        
        source_header = input_pipe->getHeader();
    }
    
    if (!options.is_subquery)
    {
        if (context->getSettingsRef().enable_global_with_statement)
            ApplyWithAliasVisitor().visit(query_ptr);
        ApplyWithSubqueryVisitor().visit(query_ptr);
    }
    JoinedTables joined_tables(getSubqueryContext(*context), getSelectQuery());
    bool got_storage_from_query = false;
    if (!has_input && !storage)
    {