abstract class AbstractEvent<T> {
    public constructor(data: T) {
        for (const key in data) {
            (this as any)[key] = data[key];
        }
    }
}

class PackCreatedEvent extends AbstractEvent<PackCreatedEvent> {
    public readonly id: string;
    public readonly title: string;
}

const packCreatedEvent1 = new PackCreatedEvent({
    id: 'x',
    title: 'y',
});

const packCreatedEvent2 = new PackCreatedEvent({
    id: 'x',
    title: 'y',

    // Causes error as desired
    foo: 'test',
});