Re: Error message using AikenHeads with NullVoice

[Jean Abou Samra]

On 7/6/22 19:56, David F. wrote:
> I have a collection of SATB hymns that I would like to engrave using shape 
> notes.  The Lilypond files are all structured the same, as seen below—treble 
> clef with music and a NullVoice for aligning lyrics, then the lyrics, then the 
> bass clef.
>
> %%%%%
> \version "2.22"
> \language “english"
>
> % included from another file
> \layout {
>      \context {
>          \Staff
>              \aikenHeads
>      }
> }
>
> \score {
>      <<
>          \new Staff <<
>              % music here
>              \new NullVoice = "melody" { e'8 fs'8 }
>          >>
>          % \new Lyrics \lyricsto "melody" { Ly -- rics }
>          % bass clef here
>      >>
>      \layout {}
> }
> %%%%%
>
> The command to use aikenHeads comes from a separate style file that gets 
> included for each hymn.  But there is an unfortunate interaction between 
> aikenHeads and NullVoice: Lilypond outputs the following error message:
>
> programming error: must have stem dir for note head
> continuing, cross fingers
>
> And it outputs a lot of these messages.  I need to find a way to stop Lilypond 
> from outputting this error.  Any kind of quick fix or hack would be sufficient.
>
> One thought I had would be to re-enable regular note heads for the NullVoice:
>
>              \new NullVoice = "melody" \with { \unset shapeNoteStyles } { e'8 
> fs'8 }
>
> But I couldn’t come up with anything that worked.
>
> Any help or ideas would be greatly appreciated.


How about changing \Staff into \Voice?

\layout {
    \context {
        \Voice
            \aikenHeads
    }
}

That way, it won't affect those NullVoice contexts.

Best,
Jean