ModelEditor behaves unexpected and crashes QC

Steps to reproduce:

• start QC with ModelEditor plugin enabled
• invoke "New File or Project...", select "Modeling" -> "Model", give it a name and a valid path
• drag a Package onto the editor, resize it
• drag a Class onto the Package
• select the Package again, hit 'Delete'
  • Package is removed from the editor, but it is still visible inside the Hierarchy view ( ? ) on top right [kind of unexpected for me (1)]
  • the Class is still listed as '(from New Package)' [kind of unexpected for me (2)]
• inside the Hierarchy View select the model, hit Ctrl+D or use context menu to trigger a deletion
• confirmation dialog comes up stating that the file has unsaved changes
• hit 'Cancel'

Current behaviour:

• QC crashes

Expected behaviours:
(1) expected that the package would get removed inside Hierarchy view as well, either including all its content (after confirmation) OR just removing the package, but keeping its content
(2) either this should have been removed as well (see above) OR it should just lose its 'parent' - the package