**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.
```


}
    else
        throw Exception("Logical error in InterpreterSelectQuery: nowhere to read", ErrorCodes::LOGICAL_ERROR);
    
    
    
    
    
    
    if (!query_plan.getMaxThreads() || is_remote)
        query_plan.setMaxThreads(max_threads_execute_query);
    
    if (processing_stage == QueryProcessingStage::FetchColumns && alias_actions)
    {
        auto table_aliases = std::make_unique<ExpressionStep>(query_plan.getCurrentDataStream(), alias_actions);
        table_aliases->setStepDescription("Add table aliases");
        query_plan.addStep(std::move(table_aliases));
    }
}
void InterpreterSelectQuery::executeWhere(QueryPlan & query_plan, const ActionsDAGPtr & expression, bool remove_filter)
{
    auto where_step = std::make_unique<FilterStep>(
            query_plan.getCurrentDataStream(),
            expression,
            getSelectQuery().where()->getColumnName(),
            remove_filter);
    where_step->setStepDescription("WHERE");
    query_plan.addStep(std::move(where_step));
}
void InterpreterSelectQuery::executeAggregation(QueryPlan & query_plan, const ActionsDAGPtr & expression, bool overflow_row, bool final, InputOrderInfoPtr group_by_info)