Kernel crash / near2far + sim-get_farfield

[cfebrian]

Simple simulation:

• Spherical wave (dipole) at the center of a 3-D box

Looking to benchmark the far field pattern against some other simulations and I hit an issue that I don't know how to resolve.

ff = sim.get_farfield(nf_box, mp.Vector3(x, y, z))

This causes a kernel crash on an Ubuntu machine. I've checked my nf_box and it seems reasonable (encloses the source and is smaller than the PMLs).

The Kernel crashed while executing code in the current cell or a previous cell. 
Please review the code in the cell(s) to identify a possible cause of the failure. 
Click [here](https://aka.ms/vscodeJupyterKernelCrash) for more info. 
View Jupyter [log](command:jupyter.viewOutput) for further details.

I'm running python 3.8.20

What should I do to address this issue:

1. Post a bug?
2. Debug by looking at ??