lastgenre fails during a full library run

[yacoob]

Simple run of beet lastgenre seems to fail before any genre is being fetched.

$ beet -vv lastgenre
user configuration: /home/yacoob/.config/beets/config.yaml
data directory: /home/yacoob/.config/beets
plugin paths:
Sending event: pluginload
inline: adding item field multidisc
lyrics: Disabling google source: no API key configured.
library database: /home/yacoob/.beetsdb
library directory: /mnt/lcl/geofront/worek/beets
Sending event: library_opened
Traceback (most recent call last):
  File "/home/yacoob/bin/beet", line 9, in <module>
    load_entry_point('beets==1.4.3', 'console_scripts', 'beet')()
  File "/home/yacoob/.venvs/beets/lib/python3.4/site-packages/beets/ui/__init__.py", line 1209, in main
    _raw_main(args)
  File "/home/yacoob/.venvs/beets/lib/python3.4/site-packages/beets/ui/__init__.py", line 1196, in _raw_main
    subcommand.func(lib, suboptions, subargs)
  File "/home/yacoob/.venvs/beets/lib/python3.4/site-packages/beetsplug/lastgenre/__init__.py", line 379, in lastgenre_func
    album.genre, src = self._get_genre(album)
  File "/home/yacoob/.venvs/beets/lib/python3.4/site-packages/beetsplug/lastgenre/__init__.py", line 321, in _get_genre
    result = self.fetch_album_genre(obj)
  File "/home/yacoob/.venvs/beets/lib/python3.4/site-packages/beetsplug/lastgenre/__init__.py", line 272, in fetch_album_genre
    u'album', LASTFM.get_album, obj.albumartist, obj.album
  File "/home/yacoob/.venvs/beets/lib/python3.4/site-packages/beetsplug/lastgenre/__init__.py", line 264, in _last_lookup
    genre = self.fetch_genre(method(*args_replaced))
  File "/home/yacoob/.venvs/beets/lib/python3.4/site-packages/beetsplug/lastgenre/__init__.py", line 227, in fetch_genre
    return self._resolve_genres(self._tags_for(lastfm_obj, min_weight))
  File "/home/yacoob/.venvs/beets/lib/python3.4/site-packages/beetsplug/lastgenre/__init__.py", line 212, in _resolve_genres
    tags = self._sort_by_depth(tags)
  File "/home/yacoob/.venvs/beets/lib/python3.4/site-packages/beetsplug/lastgenre/__init__.py", line 177, in _sort_by_depth
    depth_tag_pairs.sort(reverse=True)
TypeError: unorderable types: NoneType() < int()

I believe the plugin has been otherwise working during importing of files, as I see genres set in the library, and they're different from what the files came with. An attempt to fetch genres for the whole library, however, fails as described above.

Setup

• OS: Debian 8.7, running on top of 3.16.0-4-amd64 Finally started to get somewhere :-) #1 SMP Debian 3.16.39-1 (2016-12-30) x86_64 GNU/Linux
• Python version: 3.4.2
• beets version: 1.4.3
• Turning off plugins made problem go away (yes/no): no, it fails the same way with plugins: lastgenre alone.

My configuration (output of beet config) is:

lyrics:
    bing_lang_from: []
    google_engine_ID: REDACTED
    force: no
    genius_api_key: REDACTED
    bing_client_secret: REDACTED
    bing_lang_to:
    sources:
    - google
    - lyricwiki
    - lyrics.com
    - musixmatch
    google_API_key: REDACTED
    auto: yes
    fallback:

import:
    copy: yes
    write: yes
    resume: yes
    languages: en
library: ~/.beetsdb
directory: /mnt/lcl/geofront/worek/beets
metasync:
    source: itunes
    itunes:
        library: /home/yacoob/workarea/itunes.xml
lastgenre:
    prefer_specific: yes
    canonical: yes
    separator: ', '
    source: album
    whitelist: yes
    min_weight: 10
    count: 1
    auto: yes
    force: yes
    fallback:
per_disc_numbering: yes
original_date: yes
chroma:
    auto: no
id3v23: yes

plugins: mbsync fetchart metasync duplicates missing scrub embedart lyrics lastgenre discogs web info inline
fetchart:
    cautious: yes
    cover_names: front covert art
    fanarttv_key: REDACTED
    enforce_ratio: no
    google_engine: 001442825323518660753:hrh5ch1gjzm
    sources:
    - filesystem
    - coverart
    - itunes
    - amazon
    - albumart
    minwidth: 0
    auto: yes
    maxwidth: 0
    google_key: REDACTED
    store_source: no

paths:
    default: $albumartist/$album%aunique{}/%if{$multidisc,$disc-}$track $title
    comp: Compilations/$album%aunique{}/%if{$multidisc,$disc-}$track $title
item_fields:
    multidisc: 1 if disctotal > 1 else 0

match:
    strong_rec_thresh: 0.1
    preferred:
        countries: [US, GB|UK]
        media: [CD, Digital Media|File]
        original_year: yes
discogs:
    tokenfile: discogs_token.json
    apikey: REDACTED
    apisecret: REDACTED
    source_weight: 0.5
missing:
    count: no
    total: no
embedart:
    ifempty: no
    remove_art_file: no
    auto: yes
    maxwidth: 0
    compare_threshold: 0
    source: itunes
    itunes:
        library: /home/yacoob/workarea/itunes.xml
lastgenre:
    prefer_specific: yes
    canonical: yes
    separator: ', '
    source: album
    whitelist: yes
    min_weight: 10
    count: 1
    auto: yes
    force: yes
    fallback:
per_disc_numbering: yes
original_date: yes
chroma:
    auto: no
id3v23: yes

plugins: mbsync fetchart metasync duplicates missing scrub embedart lyrics lastgenre discogs web info inline
fetchart:
    cautious: yes
    cover_names: front covert art
    fanarttv_key: REDACTED
    enforce_ratio: no
    google_engine: 001442825323518660753:hrh5ch1gjzm
    sources:
    - filesystem
    - coverart
    - itunes
    - amazon
    - albumart
    minwidth: 0
    auto: yes
    maxwidth: 0
    google_key: REDACTED
    store_source: no

paths:
    default: $albumartist/$album%aunique{}/%if{$multidisc,$disc-}$track $title
    comp: Compilations/$album%aunique{}/%if{$multidisc,$disc-}$track $title
item_fields:
    multidisc: 1 if disctotal > 1 else 0

match:
    strong_rec_thresh: 0.1
    preferred:
        countries: [US, GB|UK]
        media: [CD, Digital Media|File]
        original_year: yes
discogs:
    tokenfile: discogs_token.json
    apikey: REDACTED
    apisecret: REDACTED
    source_weight: 0.5
missing:
    count: no
    total: no
embedart:
    ifempty: no
    remove_art_file: no
    auto: yes
    maxwidth: 0
    compare_threshold: 0
scrub:
    auto: yes
pathfields: {}
album_fields: {}
duplicates:
    keys: []
    copy: ''
    move: ''
    checksum: ''
    count: no
    path: no
    delete: no
    full: no
    album: no
    strict: no
    tag: ''
    merge: no
    format: ''
    tiebreak: {}
web:
    cors: ''
    host: 127.0.0.1
    port: 8337

Please tell me if you need any more information from me.

[yacoob]

Correction: this particular failure (exact stack trace) appears now during import as well. This probably means that the problem has been triggered by some db change, as I haven't updated beets in the meantime.

[sampsyo]

Yikes; looks like trouble. To help narrow this down, would you mind trying this out while disabling some of your lastgenre config options (e.g., prefer_specific and fallback)? That might help us understand whether a specific option is causing the crash.

[yacoob]

Your intuition was correct: this failure only happens if I set canonical: true. And come to think of it, I did switch that option on last night, just didn't connect the dots straight away.

[sampsyo]

OK, that helps! I can't reproduce the crash here just with canonical though—if I can ask you to do a little more investigation, is there any chance you can check whether the problem arises from a conflict between that and one other option?

[yacoob]

I've fiddled with prefer_specific as this is the only other option I have enabled in my config.

With

prefer_specific: yes
canonical: yes

beets crashes as above

With

prefer_specific: no
canonical: yes

Setting canonical: no stops the crashes, regardless of value of prefer_specific.

[yacoob]

Hmm, is this a subcase of #2459 ?

[sampsyo]

Hmm; yes! The traceback does seem to indicate the same root bug here. The additional evidence here will certainly be useful; thank you!