Copilot round 5: one inline comment, two suppressed. All three valid, and two
were defects from round 4's own fix.
1. Stripping the `null` sentinel from an `enum` left the parallel `enumNames`
untouched. Both renderers discard labels outright when the two lengths
disagree, so `{ enum: ["a", null], enumNames: ["Alpha", "None"] }` lost the
`Alpha` label entirely — a worse outcome than the sentinel it was fixing.
`enumNames` is now filtered by the same indices, and only when it was
positionally parallel to begin with (a mismatched list is already ignored
by both renderers, so re-indexing it would invent an alignment the server
never declared).
2. `enum: [null]` became `enum: undefined`, which widened a schema permitting
*only* `null` into a plain string field accepting arbitrary text — the form
would then invite values the schema forbids. Trading a cosmetic problem for
a correctness one, which was the wrong call. The collapse now declines
entirely for that case and the field renders through the JSON editor.
3. That JSON editor was still carrying #1928's original mechanism: it stored
unparseable text back as the *value*, which the next render
re-`JSON.stringify`d, so typing `[` gave `"["` then `"\"[\""`. Routing
nullable fields to real widgets removed the common way of landing there but
never fixed the editor — and #2007's fix deliberately sends object unions to
it, so a fallback nobody can type into is not a fallback. `SchemaJsonField`
now holds the draft text locally (the split `SchemaNumberInput` already
uses) and reports parsed JSON, or `undefined` while the text is mid-edit —
an inspector must not report a value it cannot send. Keyed by `resetKey`
like the number field, since it now holds state.
Also replaces an `as unknown as string[]` in the round-4 test, which violated
the repo's TypeScript rules and papered over `InspectorFormSchema.enum` being
unable to model a valid `["a", null]`. The fixture is wire data, so it now goes
through `toFormSchema` — the same wire→form narrowing boundary every production
call site uses.
Signed-off-by: cliffhall <cliff@futurescale.com>