Cross Staff Grace Notes rendering issue with Beaming

[arshiacont]

Two issues with the following excerpt:

1. the crossed staff grace beaming is incorrect
2. this excerpt will lead to a crash on the Destructor of GRGrace class if the corresponding instance of GRHandler is freed.

{[ \staff<1>  \barFormat<style= "system", range="1-2"> 
   (* meas. 1 *)  \clef<"g2"> \key<-1> \meter<"C/"> 
   \stemsUp f#1/2  a1/4 \stemsDown  d#2/4 \bar<measNum=2> 
   (* meas. 2 *)  f#2/2. _/4 
 ]
 , 
[ \staff<2> 
   (* meas. 1 *)  \clef<"f4"> \key<-1> \meter<"C/"> \stemsUp \grace( \beamBegin:1  b#-2/16 d#-1/16 f#-1/16 a-1/16  b#-1/16 d#0/16 f#0/16
 \beamEnd:1 \staff<1> \stemsDown \beamBegin:1 a0/16 b#0/16 d#1/16 
 \beamEnd:1)
 empty/1 \staff<2>  
   (* meas. 2 *)  \fermata( _/1)
]}

Currently rendered as

Expected similar to:

[dfober]

the crash bug is solved, but not yet the beaming issue

[arshiacont]

Thanks @dfober ! That's already much better

[dfober]

fixed