type ApiErrorShape = {
  message?: unknown;
  response?: { data?: unknown };
};

export function getErrorMessage(error: unknown, fallback: string): string {
  if (error instanceof Error && error.message) return error.message;
  if (typeof error === "object" && error !== null) {
    const message = (error as ApiErrorShape).message;
    if (typeof message === "string" && message) return message;
  }
  return fallback;
}

export function getFieldError(
  error: unknown,
  field: string,
  fallback: string,
): string {
  if (typeof error === "object" && error !== null) {
    const data = (error as ApiErrorShape).response?.data;
    if (typeof data === "object" && data !== null) {
      const value = (data as Record<string, unknown>)[field];
      if (Array.isArray(value) && typeof value[0] === "string") return value[0];
      if (typeof value === "string") return value;
    }
  }
  return getErrorMessage(error, fallback);
}