Versioning Projects

[Abe404]

When a user tries to open a multiclass RootPainter project in the single class version of RootPainter they get the following error:

Initialising RootPainter
Traceback (most recent call last):
File "/home/abe/projects/root_painter/painter/src/main/python/root_painter.py", line 381, in show_open_project_widget
self.open_project(file_path)
File "/home/abe/projects/root_painter/painter/src/main/python/root_painter.py", line 198, in open_project
last_with_annot = last_fname_with_annotations(self.image_fnames,
File "/home/abe/projects/root_painter/painter/src/main/python/file_utils.py", line 41, in last_fname_with_annotations
val_annot_fnames = os.listdir(str(val_annot_dir))
FileNotFoundError: [Errno 2] No such file or directory: '/home/abe/rp_sync_live/projects/lungs_and_spine/annotations/val'
Traceback (most recent call last):
File "/home/abe/projects/root_painter/painter/src/main/python/root_painter.py", line 381, in show_open_project_widget
self.open_project(file_path)
File "/home/abe/projects/root_painter/painter/src/main/python/root_painter.py", line 198, in open_project
last_with_annot = last_fname_with_annotations(self.image_fnames,
File "/home/abe/projects/root_painter/painter/src/main/python/file_utils.py", line 41, in last_fname_with_annotations
val_annot_fnames = os.listdir(str(val_annot_dir))
FileNotFoundError: [Errno 2] No such file or directory: '/home/abe/rp_sync_live/projects/lung_2d_multiclass/annotations/val'

Do we need to think about some type of version system to let users know that the issue is that they need to upgrade?