constructor({
        mailgunClient,
        errorHandler
    }) {
        this.#mailgunClient = mailgunClient;
        this.#errorHandler = errorHandler;
    }
@param {object} dependencies
@param {import('@tryghost/mailgun-client/lib/MailgunClient')} dependencies.mailgunClient - mailgun client to send emails
@param {Function} [dependencies.errorHandler] - custom error handler for logging exceptions