Workbench will crash when "Close Project" is called in conjunction with QmitkDataStorageComboBox being present in any plugin/tool (eg. nnUNet).
Sample workflow to replicate (Ubuntu only):
1. Load any image, goto Segmentation View
2. Click nnUNet.
3. Select "Multi Modal" checkbox -> a QmitkDataStorageComboBox appears.
4. Close Project
This leads to Segmentation fault and workbench crashes immediately.