debugLinkPayload function
Returns the payload still held by the slot for id, or an empty link.
Unlike live link resolution, this inspects zero-reference entries too, so regression tests can detect payloads retained after the last release.
Implementation
Link debugLinkPayload(int id) {
final slot = _linkRegistry.slot(id);
if (slot < 0 || slot >= _linkRegistry._slots.length) return const Link();
final entry = _linkRegistry._slots[slot];
if (entry == null || entry.id != id) return const Link();
final payload = entry.payload;
return payload == null
? const Link()
: Link(url: payload.url, params: payload.params);
}