I seem to have found an elc/bignum bug, but I'm not sure about that (and I'm having trouble getting to my computer anytime soon).
If ya has a moment, could ya try running bignum saori to try and calculate 0+0?
This might get a memory access error, so please save anything else in the programme before trying it.
https://github.com/ukatech/csaori/releases/tag/bignum_v0.0.0.1