This simple song:
will create an exported score with an extra blank measure.
The bottom of the .ly source has “undefined” which I think is causing the problem!
\new Staff \with {
instrumentName = \markup{ \smaller "Strings Whole Main " }
shortInstrumentName = \markup{"St. Wh. Ma. " }
} {
{\set Staff.extraNatural = ##f \override Lyrics.LyricSpace #'minimum-distance = #1.0 \clef treble \key c \major \time 4/4 << e'1 g'1 c''1 >> << f'1 a'1 c''1 >> << e'1 g'1 c''1 >> << g'1 b'1 d''1 >> << e'1 g'1 c''1 >>
}
}
\addlyrics{
}
undefined>>
\version "2.18.2"```