midi volume range with Hairpin

[今井雄治]

Hi, users.

I want to set volume range of midi,
so use midiMinimumVolume and midiMaximumVolume.
But I could not resolve some problems.

1st
work so good.
2nd
midi volume over the value of midiMaximumVolume.
3rd
set \f with transparent, midi volume is good, but Hairpin too short.
4th
midi volume and length of Hairpin both OK.
but some errors as following:
programming error: cannot align on self: empty element

Any idea for resolve this problem,
or remove hairpin effect for midi.

Thank you for reading.

\score {
  \relative {
    % 1st
    c 4 \p \< c c c | e e e e | g4 g g g \f
    % 2nd
    c,4 \p \< c c c | e e e e | g4 g g g \!
    % 3rd
    c,4 \p \< c c c | e e e e | g4 g g
    \once \override DynamicText #'stencil = ##f g \f
    % 4th
    c,4 \p \< c c c | e e e e | g4 g g
    \once \override DynamicText #'transparent = ##t g \f
  }
  \midi {
    \context {
      \Score
      midiMinimumVolume = #0.1
      midiMaximumVolume = #0.2
    }
  }
}