Remove all occurrencies of "0" fingerings

[Marc Hohl]

Hello list!

I wanted to write a little callback to remove all occurrencies
of "0" fingerings. This is what I got so far:


\version "2.19.63"

music = {
  c'4-3 d'-0 e'-2 f'-3 | g'1-0
}

\score {
  \new Staff \with {
    \override Fingering.stencil =
      #(lambda (grob)
         (let* ((text (ly:grob-property grob 'text))
                (stencil (if (equal? text "0")
                             empty-stencil
                             (ly:grob-property grob 'stencil))))
               stencil)) }
  { \music }
}


Compiling this nearly MWE, I get:

Warning: Fingering has empty extent and non-empty stencil.
Warning: Fingering has empty extent and non-empty stencil.

And *no* fingering at all is shown in the resulting score.
What am I doing wrong?

Regards,

Marc