**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+
}
                    else
                        parsed = tryParseImpl<ToDataType>(vec_to[i], read_buffer, local_time_zone);
                }
                if (!isAllRead(read_buffer))
                    parsed = false;
                if (!parsed)
                {
                    if constexpr (std::is_same_v<ToDataType, DataTypeDate32>)
                    {
                        vec_to[i] = -static_cast<Int32>(DateLUT::instance().getDayNumOffsetEpoch());
                    }
                    else
                    {
                        vec_to[i] = static_cast<typename ToDataType::FieldType>(0);
                    }
                }
                if constexpr (exception_mode == ConvertFromStringExceptionMode::Null)
                    (*vec_null_map_to)[i] = !parsed;
            }
            current_offset = next_offset;
        }
        if constexpr (exception_mode == ConvertFromStringExceptionMode::Null)
            return ColumnNullable::create(std::move(col_to), std::move(col_null_map_to));
        else
            return col_to;
    }
};
template <typename ToDataType, typename Name>
requires (!std::is_same_v<ToDataType, DataTypeString>)