A bug about cell groups generating

[xubaozi1307]

Dear professor，thank you for providing this excellent soft and it helps me a lot with polycrystalline modeling.
Here is a question about the tessellation. When the ratio of the two grains is 0.4/0.6, the program was aborted. However, when the scale factor is set to something else, such as 0.5/0.5, the program can run normally.I don't know if this was due to my unreasonable order.Specific information is below：

$ neper -T -n from_morpho -morpho "diameq:0.4*normal(30,10)+0.6*normal(20,7)"  -o anis30% -group mode -statgroup vol -statcell diameq -reg 1 -domain "cube(128,128,128)"  -tesrsize 64 -format tesr,tess -tesrformat ascii 

========================    N   e   p   e   r    =======================
Info   : A software package for polycrystal generation and meshing.
Info   : Version 4.5.0
Info   : Built with: gsl|muparser|opengjk|openmp|nlopt|libscotch (full)
Info   : Running on 8 threads.
Info   : <https://neper.info>
Info   : Copyright (C) 2003-2022, and GNU GPL'd, by Romain Quey.
Info   : No initialization file found (`/home/xujing/.neperrc').
Info   : ---------------------------------------------------------------
Info   : MODULE  -T loaded with arguments:
Info   : [ini file] (none)
Info   : [com line] -n from_morpho -morpho
         diameq:0.4*normal(30,10)+0.6*normal(20,7) -o anis30% -group mode
         -statgroup vol -statcell diameq -reg 1 -domain cube(128,128,128)
         -tesrsize 64 -format tesr,tess -tesrformat ascii
Info   : ---------------------------------------------------------------
Info   : Reading input data...
Info   : Creating domain...
Info   : Creating tessellation...
Info   :       . Number of cells: 191
Info   :   - Setting seeds... 100%
Info   :   - Generating crystal orientations...
Info   :   - Running tessellation...
Info   :     > Initial solution: f   =4.473839316
Info   :     > Iteration   2467: fmin=0.103961120 f=0.103961120Error  : You have discovered a bug in Neper!  Please file an issue at
         https://github.com/rquey/neper/issues.  Thank you.

Aborted (core dumped)