Unsubscribes automatically when component is destroyed.

subscription-tracker.ts

export class SubscriptionTracker {
    private subscriptions: Subscription[] = [];

    constructor(destroyable: OnDestroy) {
        const originalOnDestroy = destroyable.ngOnDestroy;
        destroyable.ngOnDestroy = () => {
            this.unsubscribeAll();
            originalOnDestroy.call(destroyable);
        };
    }

    subscribe<T>(
      observable: Observable<T>,
      observerOrNext?: PartialObserver<T> | ((value: T) => void),
      error?: (error: any) => void,
      complete?: () => void
    ): Subscription {
        const subscription = observable.subscribe(
           toSubscriber(observerOrNext, error, complete)
        );
        this.subscriptions.push(subscription);
        return subscription;
    }

    unsubscribe(subscription: Subscription) {
        subscription.unsubscribe();
        const indexOfSubscription = this.subscriptions.indexOf(subscription);
        if (indexOfSubscription == -1) {
            throw new Error("Unsubscribing to untracked subscription");
        }
        this.subscriptions.splice(indexOfSubscription, 1);
        return subscription;
    }

    unsubscribeAll() {
        this.subscriptions.forEach((subscription) => subscription.unsubscribe());
        this.subscriptions = [];
    }
}