field_object.type is wrong

Sorry, my English is not good.

I have a csv file with two empty lines.
|  |
|:-|
|  |

when I run the below code:
```
auto field = csv.next_field();
std::cout << (field.type == FieldType::DATA) << std::endl;
```

The result is `1 (true)`.
I think `field.type` should be `FieldType::ROW_END`  instead of  `FieldType::DATA`.