Fix IllegalStateException: No logical node selected!

[matthias-ronge]

Exception occurs when opening Metadata Editor, because calling method expects null in no-data case, but receives IllegalStateException:

[solth]

I think this can potentially create a NullPointerException because the result of DataEditorService.getStructuralElementView is also passed as last parameter to ProcessService.findLinkableChildProcesses where .contains is called on it without a null-check:

kitodo-production/Kitodo/src/main/java/org/kitodo/production/services/data/ProcessService.java

Line 785 in 3d4fd47

if (allowedStructuralElementTypes.contains(getBaseType(process.getId()))) {

[matthias-ronge]

No, because allowedSubstructuralElements is the result of Map.keySet() which cannot be null.

BTW, this is not the problem here. The problem was that the calling method expects null in case there is nothing (and there are severeal more correct return null; statements below in getStructuralElementView()), but in this one place the function throws an IllegalStateException instead of returning null.

[solth]

Maybe, but AddDocStrucTypeDialog.search definitely calls a method on the result of DataEditorService.getStructuralElementView (DataEditorService.getStructuralElementView(this.dataEditor).getAllowedSubstructuralElements(), to be specific), that will definitely result in a NullPointerException when getStructuralElementView is changed to return null:

kitodo-production/Kitodo/src/main/java/org/kitodo/production/forms/dataeditor/AddDocStrucTypeDialog.java

Line 634 in 0e6e0ee

Set<String> allowedSubstructuralElements = DataEditorService.getStructuralElementView(this.dataEditor)

It looks to me that the other cases where null is returned are problematic as well, because the resulting NullPointerException is not handled anywhere.

[matthias-ronge]

I also can't rule out that this will cause an error somewhere else, but for me it solved the specific stack trace problem (and maybe that's already helpful, for example to be able to see an error message). There may be more problems, but merging this would still be an improvement on before, not a deterioration overall, I think.