`kieExecutor.createTask()` returns `JsonObject` (`Record<string, unknown>`), so
`createData.data` is `unknown` and the `createData?.data?.taskId` read that
image, video and music generation each duplicated could not compile. The same
three-line expression appeared verbatim in all three handlers.
`open-sse/utils/kieTask.ts` already holds two helpers with exactly this shape —
`normalizeKieTaskState()` and `parseKieResultJson()` both take `unknown`, guard
with `isJsonObject()` and return a declared type. `getKieTaskId()` follows them,
so the three handlers now share one guarded read instead of three unguarded ones.
`getKieCallbackUrl()` took `KieCallbackBody`, a weak type (all properties
optional). Passing a request body whose declared keys are `prompt` /
`timeout_ms` / `poll_interval_ms` tripped TS2559 "no properties in common" at
both music call sites. It receives arbitrary upstream request bodies, so it now
takes `unknown` and guards the same way its neighbours do; `KieCallbackBody`
had no other reference and is gone.
Behaviour is unchanged. `isJsonObject()` rejects arrays and null exactly where
optional chaining already yielded `undefined`, and the callers' `String(taskId)`
coercion moved inside the helper, so a numeric id still reaches `pollTask()` as
a string and a falsy id still takes the 502 branch.
Fixes 5 of the 208 `tsc -p open-sse/tsconfig.json` diagnostics with no new ones:
3 x TS2339 `taskId` on `unknown`, 2 x TS2559 on `KieCallbackBody`.
Refs #8484
13e15e9cfe