Re: Wrong type argument

[Keith OHara]

> > Is it because NullVoice is has now been moved in terms of its context
> > 'position' (if that is the right word)?
> >
> > http://git.savannah.gnu.org/gitweb/?p=lilypond.git;a=commit;h=fc8c2d680464130af497c386ed5f0033d3fd7470

Yes. But we can revert that.

The commit just before that one fixed the bugs in NullVoice; then the commit 
you found moved NullVoice to Score so I wouldn't need the part of the bug-fix 
with ugly code.  I was thinking there might be more unwanted interactions 
between NullVoice and the Staff waiting to be found.

> Though, I'm not sure it's a bug. I doubt it make much sense to add an
> engraver like the solfege-engraver to NullVoice.
> I've the feeling it negates the sense of NullVoice.

The description is a place to put notes so you can attach lyrics, without 
printing the notes,
<http://www.lilypond.org/doc/v2.19/Documentation/notation/techniques-specific-to-lyrics#polyphony-with-shared-lyrics>

The bug-report in this thread was about an unforeseen use that stopped working:
in addition to Lyrics, use NullVoice to attach numbers giving the pitches.

Easier to add a bug than not
<https://code.google.com/p/lilypond/issues/detail?id=4093>