export declare type SiteKey = {
    key: string;
    instanceUrl?: URL;
};
export declare type WidgetConfig = {
    siteKey?: SiteKey;
    widgetLink?: URL;
};
export declare class ConfigurationError extends Error {
    message: string;
}
export default class Receiver {
    private updateState;
    widgetLink: URL;
    constructor(config: WidgetConfig, updateState: (token: string) => void);
    listen(): void;
    destroy(): void;
    handle: (e: MessageEvent) => void;
}