A couple of minor things I noticed in the recently-installed patch:

> const short minargs = function->min_arity;

In theory at least the arity might be greater than 32767, so this should be 
ptrdiff_t. Also, we typically don't use 'const' on locals, as it's not worth the 
screen real estate -- it should be easy even for a human reader to tell whether 
a local is assigned to later. (Likewise for 'register'.)

While looking into arity range I noticed a couple of other glitches in the 
neighborhood, and so installed the attached.