fs/io/OutputStream: use C++ exceptions in Write()

src/PlaylistSave.cxx

@@ -86,9 +86,7 @@ spl_save_queue(const char *name_utf8, const Queue &queue, Error &error)
 	for (unsigned i = 0; i < queue.GetLength(); i++)
 		playlist_print_song(bos, queue.Get(i));
 
-	if (!bos.Flush(error))
-		return false;
-
+	bos.Flush();
 	fos.Commit();
 
 	idle_add(IDLE_STORED_PLAYLIST);