'NoneType' object has no attribute 'underlying_book_id'

[ownedbycats]

8.15, if I edit any composite column (even no changes) it makes this error:

calibre, version 8.15.0
ERROR: Unhandled exception: <b>AttributeError</b>:'NoneType' object has no attribute 'underlying_book_id'

calibre 8.15 embedded-python: True
Windows-10-10.0.19045-SP0 Windows ('64bit', 'WindowsPE')
('Windows', '10', '10.0.19045')
Python 3.11.14
Windows: ('10', '10.0.19045', 'SP0', 'Multiprocessor Free')
Interface language: None
EXE path: C:\Program Files\Calibre2\calibre.exe
Successfully initialized third party plugins: ...
Traceback (most recent call last):
  File "calibre\gui2\library\delegates.py", line 213, in createEditor
AttributeError: 'NoneType' object has no attribute 'underlying_book_id'

[Kovid Goyal (kovid)]

Fixed in branch master. The fix will be in the next release. calibre is usually released every alternate Friday.