define-music-function with afterGrace and {}

[jcarll]

Good day,

following snippet I need very frequently (with different notes instead
of c4 and e4):

   \afterGrace c4 \glissando {\once \hide Stem \parenthesize e4}


That's why I wanted to create a music function to shorten the
expression. My previous attempt:

   graceGliss =
   #(define-music-function
      (starttone endtone)
      (ly:music? ly:music?)
      #{
        \afterGrace #starttone \glissando {\once \hide Stem
   \parenthesize #endtone}
      #})


doesn't work, Return Code 1.

In order to test the general functioning of define-music-function, I tried:

   graceGliss =
   #(define-music-function
      (starttone endtone)
      (ly:music? ly:music?)
      #{
        \afterGrace #starttone #endtone
      #})


which works, what leads me to believe that the error must have something
to do with the curly brackets {} …


For some help I'd be very grateful!
Jonathan