LaunchDarkly feature flag service in Angular using RxJS

feature-flag.service.ts

import { Injectable, OnDestroy } from '@angular/core';
import { environment } from '@environments/environment';
import * as LaunchDarkly from 'launchdarkly-js-client-sdk';
import { LDFlagValue } from 'launchdarkly-js-client-sdk';
import { Observable, Subject } from 'rxjs';
import { map } from 'rxjs/operators';

@Injectable({
    providedIn: 'root'
})
export class FeatureFlagService implements OnDestroy {
    client: LaunchDarkly.LDClient;

    async ngOnDestroy() {
        // attempt to flush any buffered events 
        await this.client.flush();
    }

    initialize(): void {
        /* consider replacing this with a method to get the current user and map it to a context */
        const context = {
            {
                kind: "user"
                anonymous: true
            }
        };
        this.client = LaunchDarkly.initialize(environment.launchDarklyClientId, context, {
            // uncomment to cache flags in local storage
            // bootstrap: "localStorage"
        });
    }

    getFlag(flagKey: string, defaultValue: LDFlagValue = false): Observable<LDFlagValue> {
        const fetchFlag = new Subject<void>();
        this.client.on(`change:${flagKey}`, () => {
            fetchFlag.next();
        });
        // Maximum time to wait for init before contining anyway
        const TIMEOUT_SECONDS = 1;
        this.client.waitForInitialization(TIMEOUT_SECONDS)
            .catch(e => {
               console.error("permanent error during initialization, cached or fallback values will be returned")
            }).then(() => {
            fetchFlag.next();
        });
        return fetchFlag.pipe(
            map(() => {
                return this.client.variation(flagKey, defaultValue);
            })
        );
    }
}