loadPreview method
Implementation
Future<MiniProgramMediaPreviewResult> loadPreview({
required String miniProgramId,
required String mediaRef,
}) {
_ensureActive();
final normalized = _validReference(mediaRef);
requireOwned(miniProgramId, <String>[normalized]);
return _previews.putIfAbsent(
normalized,
() => _loadPreview(miniProgramId, normalized),
);
}