interface implementation faults

export enum PaymentDevice {
    'mobile' = 'mobile',
    'desktop' = 'desktop',
}

export interface PaymentError {
    redirectTo: string;
    message: string;
    paymentGatewayResponse: any;
}

export interface IPaymentService {
    device: PaymentDevice;
    redirectUrl: string;
    errorResponse?: PaymentError;
    createPaymentGateway(
        payment: CreatePaymentGatewayInput,
    ): string;
    verifyPayment(): boolean;
}

interface CreatePaymentGatewayInput {
    amount: number;
    description: string;
    phoneNumber: string;
    email: string;
}

export class ZarinpalPaymentGatewayService
    implements IPaymentService
{
    #device?: PaymentDevice;
    #errorResponse?: PaymentError;
    #redirectUrl?: string;

    set device(device: PaymentDevice) {
        this.#device = device;
    }

    get device() {
        if (!this.#device) {
            throw new Error('E_EMPTY_DEVICE')
        }
        return this.#device;
    }

    set redirectUrl(redirectUrl: string) {
        this.#redirectUrl = redirectUrl;
    }

    get redirectUrl() {
        if (!this.#redirectUrl) {
            throw new Error('E_EMPTY_REDIRECT_URL')
        }
        return this.#redirectUrl;
    }

    verifyPayment() {
        return true;
    }
    // Why it does not show me an error for empty function parameter?
    createPaymentGateway() {
        const url =
            'https://www.zarinpal.com/pg/StartPay/$Authority';
        // const {} = payment;
        return '';
    }
}