Anyway, this compiles fine here:
\version "2.18.2"
soprano = { a' }
alto = { c' }
tenor = { a }
bass = { \clef bass c }
verseOne = \lyricmode { Ah! }
\score {
\new ChoirStaff <<
\new Staff \with {
midiInstrument = "choir aahs"
instrumentName = \markup \center-column { Sopran Alt }
} <<
\new Voice = "soprano" \with {
\remove "Note_heads_engraver"
\consists "Completion_heads_engraver"
\remove "Rest_engraver"
\consists "Completion_rest_engraver"
} { \voiceOne \soprano }
\new Voice = "alto" { \voiceTwo \alto }
>>
\new Lyrics \with {
\override VerticalAxisGroup #'staff-affinity = #CENTER
} \lyricsto "soprano" \verseOne
\new Staff \with {
midiInstrument = "choir aahs"
instrumentName = \markup \center-column { Tenor Bass }
} <<
\clef bass
\new Voice = "tenor" { \voiceOne \tenor }
\new Voice = "bass" { \voiceTwo \bass }
>>
>>
\layout { }
\midi { }
}