I expect it should work:
```
:) select CAST(CAST('{"x" : 1}', 'Object(\'json\')'), 'Object(Nullable(\'json\'))')

SELECT CAST(CAST('{"x" : 1}', 'Object(\'json\')'), 'Object(Nullable(\'json\'))')

Query id: fb057b45-b72a-4d22-9b38-a3136cdf2465


0 rows in set. Elapsed: 0.002 sec.

Received exception from server (version 22.5.1):
Code: 53. DB::Exception: Received from localhost:9000. DB::Exception: Cast to Object can be performed only from flatten named Tuple, Map or String. Got: Object('json'): While processing CAST(CAST('{"x" : 1}', 'Object(\'json\')'), 'Object(Nullable(\'json\'))'). (TYPE_MISMATCH)
```

@CurtizJ what do you think?
}
                        if constexpr (std::is_same_v<Additions, AccurateOrNullConvertStrategyAdditions>
                                || std::is_same_v<Additions, AccurateConvertStrategyAdditions>)
                        {
                            bool convert_result = accurate::convertNumeric(vec_from[i], vec_to[i]);
                            if (!convert_result)
                            {
                                if (std::is_same_v<Additions, AccurateOrNullConvertStrategyAdditions>)
                                {
                                    vec_to[i] = 0;
                                    (*vec_null_map_to)[i] = true;
                                }
                                else
                                {
                                    throw Exception(
                                        "Value in column " + named_from.column->getName() + " cannot be safely converted into type "
                                            + result_type->getName(),
                                        ErrorCodes::CANNOT_CONVERT_TYPE);
                                }
                            }
                        }
                        else
                        {
                            vec_to[i] = static_cast<ToFieldType>(vec_from[i]);
                        }
                    }
                }
            }
            if constexpr (std::is_same_v<Additions, AccurateOrNullConvertStrategyAdditions>)
                return ColumnNullable::create(std::move(col_to), std::move(col_null_map_to));