Standalone viewer: 'raw_dialog' referenced before assignment

[DanicaSTFC]

When I upload a raw image correctly, I then try to uplaod another raw image (or the same again) and I get the following error

Traceback (most recent call last):
  File "...cilviewer\lib\site-packages\ccpi\viewer\standalone_viewer.py", line 52, in <lambda>
    image1_action.triggered.connect(lambda: self.setViewersInputFromDialog(self.viewers))
  File "...cilviewer\lib\site-packages\ccpi\viewer\ui\main_windows.py", line 260, in setViewersInputFromDialog
    image_file = self.selectImage()
  File "...cilviewer\lib\site-packages\ccpi\viewer\ui\main_windows.py", line 187, in selectImage
    raw_dialog.exec()
UnboundLocalError: local variable 'raw_dialog' referenced before assignment