Issue 1706 in lilypond: Beaming causes lilypond to crash

[lilypond]

Status: Accepted
Owner: ----
Labels: Type-Defect Priority-Critical Regression

New issue 1706 by address@hidden: Beaming causes lilypond to  
crash
http://code.google.com/p/lilypond/issues/detail?id=1706

Reported by Stefan Thomas:

the following code works fine in 2.12.3. but doesn't in 2.14.1.
Is there a possibility to get it working in 2.14.1?

\version "2.14.1"

music = {
  \clef bass r2 r4 r8 f,
  r2 r4 g,8 r
  r4 f, 8 r8 r2
}

beams = {
  \repeat "unfold" 24 { s8[ s ] s[ s]} % this line causes the error!
}

\new Staff {
  \context Voice << { \beams } { \music}>>
}

His "doesn't work" should be read as "causes LilyPond to crash".  Marking  
this as critical, because even though it seems slightly odd code to me, we  
shouldn't respond by crashing LilyPond.  Error messages include:

file.ly:10:33: programming error: must have Item for spanner bound of Beam
  \repeat "unfold" 24 { s8[ s ] s
                                 [ s]} % this line causes the error!

Preprocessing graphical objects...
programming error: Grob direction requested while calculation in progress.
continuing, cross fingers