export class UnfoldingFatalError extends Error { readonly code: string; readonly causeDetail?: string; constructor(code: string, message: string, causeDetail?: string) { super(message); this.name = "UnfoldingFatalError"; this.code = code; this.causeDetail = causeDetail; } } export function isUnfoldingFatalError(error: unknown): error is UnfoldingFatalError { return error instanceof UnfoldingFatalError; }