LokiDB persistenceAdapter error

I get this error when setting up LokiDB.
ERROR Error: Uncaught (in promise): Error: persistenceAdapter not configured.

import {Loki} from "@lokidb/loki";
export class LokiService {
    db: any; // LokiJS database
    constructor() {
        console.log('Loki initialization');
        this.db = new Loki('db', {env:"CORDOVA"});
    }