INSERT INTO strawberry.playlist_items
   (ROWID,
   playlist,
   collection_id,
   title,
   album,
   artist,
   albumartist,
   track,
   disc,
   year,
   originalyear,
   genre,
   compilation,
   composer,
   performer,
   grouping,
   comment,
   lyrics,
   beginning,
   length,
   bitrate,
   samplerate,
   directory_id,
   url,
   filetype,
   filesize,
   mtime,
   ctime,
   unavailable,
   playcount,
   skipcount,
   lastplayed,
   compilation_detected,
   compilation_on,
   compilation_off,
   compilation_effective,
   art_automatic,
   art_manual,
   effective_albumartist,
   effective_originalyear,
   cue_path,
   rating
   )
   SELECT ROWID,
      playlist,
      library_id,
      title,
      album,
      artist,
      albumartist,
      track,
      disc,
      year,
      originalyear,
      genre,
      compilation,
      composer,
      performer,
      grouping,
      comment,
      lyrics,
      beginning,
      length,
      bitrate,
      samplerate,
      directory,
      COALESCE(filename, ) AS url,
      filetype,
      filesize,
      mtime,
      ctime,
      unavailable,
      playcount,
      skipcount,
      lastplayed,
      sampler,
      forced_compilation_on,
      forced_compilation_off,
      effective_compilation,
      art_automatic,
      REPLACE(art_manual, '.config/Clementine/albumcovers','.local/share/strawberry/strawberry/collectionalbumcovers') AS art_manual,
      effective_albumartist,
      effective_originalyear,
      cue_path,
      rating FROM clementine.playlist_items WHERE type = 'Library';

sqlite3 throws an error:

Parse error near line 25: near ")": syntax error
  lerate,       directory,       COALESCE(filename, ) AS url,       filetype,   
                                      error here ---^

I don't know how to remedy this, I am not well versed in SQL, I only know that COALESCE takes at least two arguments, and I don't think that a space is considered an argument. But what else should be there?
Thanks for your help!