cl-slug's functions declare their arguments' full types, which SBCL
checks on entry and warns about for a constant. half-float-bits takes
only a real that rounds to a finite half, and half-float-value only a
finite half's bits, so both signal a type-error where they signalled a
slug-error. The copy functions take a row up to 65535 and a count up
to 65536. The errors page says so and drops half-float-value's row,
and the API reference gives the ranges.
Follow cl-slug 73be4fe: the requirements, the tests and CI name SBCL
alone. A fill rule given to store-add that is not :nonzero or
:even-odd is a type-error, so the slug-error for a fill rule is for the
one store-find-or-add's function returns.
