A build check error in the area "The smoke run". An error: the game cannot be published until it is fixed.
The build check runs on every game LobbyLab builds, and each problem it finds has a stable code, the exact message, the file and line when it names one, and a link to this page.
What the check looks at
The check plays the game once: init, joins for minimumPlayers, the host's start, every smoke intent, then a view per player. Every call must return small plain JSON within its CPU budget (init and advance 25 ms, project 15 ms).
How to fix it
Make each rulebook function total: accept unknown lifecycle events unchanged, reject bad intents with a short code instead of throwing, and return plain JSON (no undefined, NaN, classes or cycles).
See also: every error code, the API reference and the docs.