**Describe what's wrong**

```sql
SELECT toTypeName(s), toString(s) FROM
(
 SELECT toFixedString('',32) AS s 
 UNION ALL
 SELECT null AS s 
)
```

this query works in all versions from 19.17 to 21.8, but stop works after 21.9+ 

https://fiddle.clickhouse.com/7bd65b36-a6e6-470a-8bdc-4c98a33ff453
21.8 works

https://fiddle.clickhouse.com/9e40a424-4027-4c7f-bd41-b20935ae9129
21.9 doesn't work
```
Received exception from server (version 21.9.6):
Code: 44. DB::Exception: Received from localhost:9000. DB::Exception: Illegal column Nullable(FixedString(32)) of first argument of function toString. (ILLEGAL_COLUMN)
```

this query works in all versions

```sql
SELECT toTypeName(s), toString(s) FROM
(
 SELECT '' AS s 
 UNION ALL
 SELECT null AS s 
)
```
https://fiddle.clickhouse.com/4f810f03-1644-4eb7-b696-0341b1bbdbc4


**Does it reproduce on recent release?**
Yes, reproduce in all releases 21.9+
{
public:
    using MonotonicityForRange = FunctionCastBase::MonotonicityForRange;
    template <typename DataType>
    static auto monotonicityForType(const DataType * const)
    {
        return FunctionTo<DataType>::Type::Monotonic::get;
    }
    static MonotonicityForRange getMonotonicityInformation(const DataTypePtr & from_type, const IDataType * to_type)
    {
        if (const auto * type = checkAndGetDataType<DataTypeUInt8>(to_type))
            return monotonicityForType(type);
        if (const auto * type = checkAndGetDataType<DataTypeUInt16>(to_type))
            return monotonicityForType(type);
        if (const auto * type = checkAndGetDataType<DataTypeUInt32>(to_type))
            return monotonicityForType(type);
        if (const auto * type = checkAndGetDataType<DataTypeUInt64>(to_type))
            return monotonicityForType(type);
        if (const auto * type = checkAndGetDataType<DataTypeUInt128>(to_type))
            return monotonicityForType(type);
        if (const auto * type = checkAndGetDataType<DataTypeUInt256>(to_type))
            return monotonicityForType(type);
        if (const auto * type = checkAndGetDataType<DataTypeInt8>(to_type))
            return monotonicityForType(type);
        if (const auto * type = checkAndGetDataType<DataTypeInt16>(to_type))
            return monotonicityForType(type);
        if (const auto * type = checkAndGetDataType<DataTypeInt32>(to_type))
            return monotonicityForType(type);
        if (const auto * type = checkAndGetDataType<DataTypeInt64>(to_type))