ReferenceError: Can't find variable: A0SHA256ChallengeGenerator about nativescript-auth0 HOT 3 OPEN

// crypto-es to use base64 and sha256 encryption.
import CryptoES from 'crypto-es';
const Base64 = CryptoES.enc.Base64;
const sha256 = CryptoES.SHA256;

getRandomValues(size) {
    size = size >= 43 && size <= 128 ? size : 128;

    let benchStr = '';
    const possible = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    for (let i = 0; i < size; i++) {
      benchStr += possible.charAt(Math.floor(Math.random() * possible.length));
    }

    return benchStr;
}

handler(redirectURL) {
        if (this.responseType.indexOf(ResponseType.code) > -1) {
            const authentication = new Auth0Authentication(this.clientId, this.url, this.telemetry);
            authentication.logger = this.logger;
            const verifier = this.getRandomValues(32)
            const challenge = Base64.stringify(sha256(verifier)).replace(/\+/g, '-').replace(/\//g, '_').replace(/=/g, '');

            return new PKCE(authentication, redirectURL, verifier, challenge, 'S256', this.responseType, this.nonce);
            // return PKCE.init(authentication, redirectURL, this.responseType, this.nonce);
        }
        else {
            return new ImplicitGrant(this.responseType, this.nonce);
        }
    }