KeyError Traceback on closing an unmodified new task editor

[nekohayo]

Post GTK4 port, in git master:

1. Click the + button to create a new Task Editor window
2. Without making any changes, press the Escape key

Traceback (most recent call last):
  File "GTG/gtk/editor/editor.py", line 889, in destruction
    self.app.ds.tasks.remove(tid)
  File "GTG/core/tasks.py", line 914, in remove
    item = self.lookup[item_id]
           ~~~~~~~~~~~^^^^^^^^^
KeyError: UUID('d1313822-295b-478b-932c-19ea1c7b4178')

What is strange is that the "traceback catcher" error handling GUI doesn't even catch this traceback...