unknown file: Unexpected end of file

method imageData() doesn't work for `.NEF` file

I got this error

`unknown file: Unexpected end of file`

metadata 
```
    "width": 5600,
    "height": 3728,
    "raw_width": 5600,
    "raw_height": 3728,
    "camera_make": "Nikon",
    "camera_model": "Z 50",
```