When an artist sorted name only consists of 1 word (e.g., "Josquin" (for Josquin des Prez"), the plugin throws an exception.

Here's an example:

Traceback (most recent call last):
  File "coverart_init_.py", line 144, in next_in_queue
StopIteration

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "album.py", line 407, in _finalize_loading_track
  File "metadata.py", line 655, in run_track_metadata_processors
  File "plugin.py", line 257, in run
  File "C:\Users\Xxx\AppData\Local\MusicBrainz\Picard\plugins\abbreviate_artistsort.zipabbreviate_artistsort.py", line 138, in abbreviate_artistsort
    while surname.split(None, 1)[0] == unsort.split(None, 1)[0]:
IndexError: list index out of range
Traceback (most recent call last):
  File "coverart_init_.py", line 144, in next_in_queue
StopIteration

Consider checking for this edge case everywhere in the plugin.

I also created a ticket on Github: https://github.com/metabrainz/picard-plugins/issues/350