FTS = Full-text search. It's a table only used for the collection search.
Error probably means that the rowid it's trying to insert into songs_fts already exists, which is very strange, unless you have manually modified the database.
Try re-creating the songs_fts data, with the following commands:
Remove all songs_fts data:delete from songs_fts;
Re-create songs_fts data from songs:INSERT INTO songs_fts (ROWID, ftstitle, ftsalbum, ftsartist, ftsalbumartist, ftscomposer, ftsperformer, ftsgrouping, ftsgenre, ftscomment) SELECT ROWID, title, album, artist, albumartist, composer, performer, grouping, genre, comment FROM songs;