Unterminated beam causes intimidating programming errors
From #6369 (closed):
\version "2.23.10"
{ c'8[ }
GNU LilyPond 2.23.11 (running Guile 2.2)
Processing `/home/user/lilypond-src/open-beam-at-end.ly'
Parsing...
Interpreting music...
/home/user/lilypond-src/open-beam-at-end.ly:2:6: warning: unterminated beam
{ c'8
[ }
Preprocessing graphical objects...
/home/user/lilypond-src/open-beam-at-end.ly:2:3: programming error: cyclic dependency: calculation-in-progress encountered for Stem.direction
{
c'8[ }
/home/user/lilypond-src/open-beam-at-end.ly:2:3: continuing, cross fingers
/home/user/lilypond-src/open-beam-at-end.ly:2:3: warning: direction of grob Stem must be UP or DOWN; using UP
{
c'8[ }
Finding the ideal number of pages...
Fitting music on 1 page...
Drawing systems...
Converting to `open-beam-at-end.pdf'...
Success: compilation successfully completed
Since an unterminated beam is easy to get (for example when compiling the part of a score that has been entered so far, if it has a beam extending until a part not yet entered), it'd be nice if this situation didn't cause programming errors. These are emitted in 2.23 because of 15e9d301.