version 21.5.5.12 (official build)

I'm trying to change data type for a column that is used in the TTL expression.
It works well when the table is empty.
When the table is not empty, the mutation fails.
As a result the table ends up in an inconsistent state.

```
create table test
(
InsertionDateTime DateTime,
TTLDays Int32 DEFAULT CAST(365, 'Int32')
)
Engine=MergeTree()
order by tuple()
TTL InsertionDateTime + toIntervalDay(TTLDays);

Ok.

insert into test values (now(), 23);

Ok.

ALTER TABLE test modify column TTLDays Int16 DEFAULT CAST(365, 'Int16');

Code: 341, e.displayText() = DB::Exception: Exception happened during execution of mutation 'mutation_2.txt' with part 'all_1_1_0' reason: 'Code: 10, e.displayText() = DB::Exception: Not found column InsertionDateTime in block. There are only columns: TTLDays (version 21.5.5.12 (official build))'. This error maybe retryable or not. In case of unretryable error, mutation can be killed with KILL MUTATION query (version 21.5.5.12 (official build)) [DB Errorcode=341]

insert into test values (now(), 23);

Ok.

select table, column, type, sum(rows) rows, sum(column_bytes_on_disk) on_disk
from system.parts_columns where column like 'TTLDays'
group by database, table, column, type

table | column  | type  | rows | on_disk
------+---------+-------+------+--------
test  | TTLDays | Int32 |    1 |      86
test  | TTLDays | Int16 |    1 |      84
```
BlockInputStreamPtr & input_stream,
    const NameSet & updated_columns,
    const StorageMetadataPtr & metadata_snapshot,
    ContextPtr context,
    const NameSet & materialized_indices,
    const MergeTreeData::DataPartPtr & source_part)
{
    
    const auto & index_factory = MergeTreeIndexFactory::instance();
    std::set<MergeTreeIndexPtr> indices_to_recalc;
    ASTPtr indices_recalc_expr_list = std::make_shared<ASTExpressionList>();
    const auto & indices = metadata_snapshot->getSecondaryIndices();
    for (size_t i = 0; i < indices.size(); ++i)
    {
        const auto & index = indices[i];
        
        if (!source_part->checksums.has(INDEX_FILE_PREFIX + index.name + ".idx") && materialized_indices.count(index.name))
        {
            if (indices_to_recalc.insert(index_factory.get(index)).second)
            {
                ASTPtr expr_list = index.expression_list_ast->clone();