export type ErrorCode = 'config' | 'key_source_unavailable' | 'no_credential' | 'malformed_credential' | 'token_malformed' | 'key_not_found' | 'signature' | 'expired' | 'not_yet_valid' | 'issuer' | 'token_class' | 'cross_origin';
export declare class UserspaceError extends Error {
    readonly code: ErrorCode;
    constructor(code: ErrorCode, message: string);
}
export declare const fail: (code: ErrorCode, message: string) => never;
export declare const isCode: (err: unknown, code: ErrorCode) => boolean;