Function assertEngineExists

app/core/Engine.ts:1677–1683

* Assert that the given Engine instance has been initialized * * @param instance - Either an Engine instance, or null

(
  instance: Engine | null,
)

 * @param instance - Either an Engine instance, or null
 */
function assertEngineExists(
  instance: Engine | null,
): asserts instance is Engine {
  if (!instance) {
    throw new Error('Engine does not exist');
  }
}

let instance: Engine | null;