Singelton EventEmitter in TypeScript

EventEmitter.ts

// based on different implementations from this thread https://gist.github.com/mudge/5830382

export type Listener = (...args: any[]) => void;
export type Events = Record<string, Set<Listener>>;
class EventEmitter {
    private events: Events = {};

    on(event: string, listener: Listener) {
        if (typeof this.events[event] !== "object") {
            this.events[event] = new Set();
        }
        this.events[event].add(listener);
        return () => this.removeListener(event, listener);
    }
    once(event: string, listener: Listener) {
        const remove = this.on(event, (...args: any[]) => {
            remove();
            listener.apply(this, args);
        });
    }
    emit(event: string, ...args: any[]) {
        if (typeof this.events[event] !== "object") {
            return;
        }
        const listeners = Array.from(this.events[event]);
        listeners.forEach((listener) => listener.apply(this, args));
    }

    removeListener(event: string, listener: Listener) {
        if (typeof this.events[event] !== "object") {
            return;
        }
        this.events[event].delete(listener);
    }
    removeAllListeners() {
        Object.keys(this.events).forEach((event) => this.events[event].clear());
    }
}

const instance = new EventEmitter();
Object.freeze(instance);

export default instance;