Make the numeric-OID cases of regprocin and friends be non-throwing.

Make the numeric-OID cases of regprocin and friends be non-throwing.

While at it, use a common subroutine already.

This doesn't move the needle very far in terms of making these
functions non-throwing; the only case we're now able to trap is
numeric-OID-is-out-of-range.  Still, it seems like a pretty
non-controversial step in that direction.