scorepaper = \paper { }

#(define staffcount 0)

\relative c' {
  \override Staff.StaffSymbol.after-line-breaking =
    #(lambda (grob)
       (set! staffcount (+ staffcount 1))
       (let* ((staff-width (interval-length (ly:grob-property grob 'X-extent)))
              (staff-space (ly:output-def-lookup scorepaper 'staff-space))
              (paper-width (ly:output-def-lookup scorepaper 'paper-width))
              (my-width (/ paper-width staff-space)))
         (if (> staff-width my-width)
             (ly:error "Music overflows page at staff ~a." staffcount))))
  %% uncomment this and compilation will fail, throwing a music overflow error.
  %r4 
  \repeat unfold 100 { c1 }
}