[Terisa de morgan]

Hi,

I was editing a file as usual and, after checking errors and correct automatic mistakes, this exception appear: "AttributeError: 'NoneType' object has no attribute 'partition'", and, after that, the books is not editable any more, with the following debug trace:

Spoiler:

calibre, version 3.22.1
ERROR: Excepción no considerada: <b>AttributeError</b>:'NoneType' object has no attribute 'partition'

calibre 3.22.1 [64bit] embedded-python: True is64bit: True
Windows-10-10.0.16299-SP0 Windows ('64bit', 'WindowsPE')
('Windows', '10', '10.0.16299')
Python 2.7.12+
Windows: ('10', '10.0.16299', 'SP0', u'Multiprocessor Free')
Interface language: es
Successfully initialized third party plugins: Gather KFX-ZIP File Type (from KFX Input) (1, 3, 0) && DeDRM (6, 6, 0) && Package KFX File Type (from KFX Input) (1, 3, 0) && Owned Books Goodreads (0, 0, 6) && NormComment (0, 0, 2) && KFX metadata reader (from KFX Input) (1, 3, 0) && KFX Input (1, 3, 0) && My Tools (0, 0, 28) && GoodreadsAuthor (0, 0, 1) && Overdrive Link (2, 26, 0) && EpubSplit (2, 4, 0) && Search Switcher (1, 0, 0) && Generate Cover (1, 5, 21) && Extract ISBN (1, 4, 5) && Kobo Books (1, 3, 1) && Count Pages (1, 8, 1) && Reading List (1, 6, 6) && View Manager (1, 4, 3) && Ex Libris (1, 0, 20) && Save Composite Custom Columns (1, 1, 0) && Diaps Editing Toolbag (0, 3, 5) && Find Duplicates (1, 6, 3) && EpubMerge (2, 2, 0) && Virtual Library Switcher (1, 0, 0) && Import List (1, 3, 0) && Barnes & Noble (1, 2, 15) && Goodreads (1, 1, 14) && Search The Internet (1, 7, 6) && KoboTouchExtended (3, 0, 2) && Goodreads Sync (1, 12, 1) && SmartEject (2, 1, 0) && Edit Columns (0, 0, 1) && Annotations (1, 7, 1) && Modify ePub (1, 4, 4) && Favourites Menu (1, 0, 4) && Kobo Utilities (2, 6, 3) && GetFileName (0, 2, 13) && Quality Check (1, 9, 11) && Fantastic Fiction (1, 2, 0)
Traceback (most recent call last):
File "site-packages\calibre\gui2\__init__.py", line 460, in dispatch
File "site-packages\calibre\gui2\tweak_book\job.py", line 86, in job_done
File "site-packages\calibre\gui2\tweak_book\boss.py", line 339, in book_opened
File "site-packages\calibre\gui2\tweak_book\file_list.py", line 981, in build
File "site-packages\calibre\gui2\tweak_book\file_list.py", line 345, in build
File "site-packages\calibre\ebooks\oeb\polish\cover.py", line 72, in get_cover_page_name
File "site-packages\calibre\ebooks\oeb\polish\cover.py", line 267, in find_cover_page
File "site-packages\calibre\ebooks\oeb\polish\toc.py", line 325, in get_landmarks
File "site-packages\calibre\ebooks\oeb\polish\toc.py", line 314, in get_nav_landmarks
AttributeError: 'NoneType' object has no attribute 'partition'