This handles issue 1035, but instead of aborting, it just raises a warning.
This seems more appropriate, because all other possible problems within
determine-frets-and-strings are handled by warnings, too.
(let ((this-fret (calc-fret (ly:event-property note 'pitch)
string
tuning)))
(let ((this-fret (calc-fret (ly:event-property note 'pitch)
string
tuning)))
+ (if (< this-fret 0)
+ (ly:warning (_ "Negative fret for pitch ~a on string ~a")
+ (note-pitch note) string))
(set! string-fret-fingering-tuples
(cons (list string
this-fret
(set! string-fret-fingering-tuples
(cons (list string
this-fret