NOTE: As it turned out, it is not as easy to reproduce as initially thought, as most times a surface of a single slice segmentation can indeed be created. We can provide an example scene file which we do not attach here because of its huge filesize.
To reproduce:
- Open an image and create a segmentation, draw a single slice
- Right-click on the segmentation in the Data Manager, choose "Create polygon model" (**not** the smoothed version) and notice that the generated surface "Label 1" is an empty surface
- Save the project and notice the output in the terminal that IOUtil won't write empty files
- In the index.xml of the generated project file (is a .zip file with .mitk extension) the node is still references with the file attribute set to an empty string
- Load the project file again, crash {icon bomb}, since our loading code doesn't handle the case when the file attribute mentioned above is empty
So we have two issues here that we need to solve:
1. Either actually write an empty surface to the project file or if we decide not to do, don't create an entry for it in the index
2. Make our loading routine more robust