It is hard to say what exactly is going wrong, but a crash at the first Voronoi-mesh construction generally hints towards a problem with the positions.
The only thing I notice here that might go wrong is that usually numpy.linspace has by default endpoint=True, which means e.g. that you include both 0 and 2 pi as points in your phi array. This might lead to two points with identical coordinates. Adding endpoint=False should help, if this is the problem.
A few other things to check:
– all positions are in between 0 and Boxsize
– there are no two identical positions
– the assumed Boxsize in create.py is identical to the one in param.txt
– visualizing the positions, there are no empty regions
Let me know if any of this solves your problem.