**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+
WrapperType && wrapper_function_, const char * name_, std::optional<Diagnostic> diagnostic_)
            : wrapper_function(std::move(wrapper_function_)), name(name_), diagnostic(std::move(diagnostic_)) {}
    String getName() const override { return name; }
protected:
    ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, size_t input_rows_count) const override
    {
        
        ColumnsWithTypeAndName new_arguments{arguments.front()};
        if (arguments.size() > 2)
            new_arguments.insert(std::end(new_arguments), std::next(std::begin(arguments), 2), std::end(arguments));
        try
        {
            return wrapper_function(new_arguments, result_type, nullptr, input_rows_count);
        }
        catch (Exception & e)
        {
            if (diagnostic)
                e.addMessage("while converting source column " + backQuoteIfNeed(diagnostic->column_from) +
                             " to destination column " + backQuoteIfNeed(diagnostic->column_to));
            throw;
        }
    }
    bool useDefaultImplementationForNulls() const override { return false; }