You've found the right place for a fix, but the fix is not correct.
param->type may not be an array, and reading param->type->array.members isn't
valid in that case. I think what we really want to check here is that the param
we're looking at is the last one, so perhaps condition like
`if (param && !param->next && fntype->func.variadism == VARIADISM_HARE)` would
be worth trying out.