···113113 * @param port The port to listen on.
114114 * @param callback A callback to run when the server is started.
115115 */
116116- start(port: number, callback: () => void = () => {}) {
116116+ start(port: number, callback: (error: Error | null, address: string) => void = () => {}) {
117117 this.app.listen({ port }, callback);
118118 }
119119