`anyOfAdmitsNull` sent every non-object member to `toBranch` and refused it,
so `{ const: null, anyOf: [true] }` read as non-nullable — a required field
seeded and rendered read-only as `null` and reported missing forever. `true`
is the unconstrained schema and admits every value, `null` among them;
`false` admits none and still does not.
Signed-off-by: cliffhall <cliff@futurescale.com>
6ac45d9b26