I ran into these two small fixes I needed to do to the generated .d.ts file for the engine:
add to Application:
lightmapper: pc.Lightmapper;
change the first param of Lightmapper.back to allow null:
bake(nodes: pc.Entity[] | null, mode?: number): void;
Also, the current tags.add() only allows a single string parameter, not an array, and not an arbitrary list of params.
(Sorry, I don’t have time to fix this properly and submit a PR, and wanted to drop it here before I forget)