/**
 * @param {unknown} err
 * @param {string} fallback
 */
export function apiErrorMessage(err, fallback) {
  const e = err && typeof err === "object" && "response" in err ? err : null;
  const data = e?.response?.data;
  if (typeof data === "string" && data.trim()) return data;
  if (data && typeof data === "object") {
    if (typeof data.message === "string" && data.message.trim()) return data.message;
    if (Array.isArray(data.errors)) {
      const parts = data.errors
        .map((x) => (x && typeof x === "object" ? x.defaultMessage || x.message : null))
        .filter(Boolean);
      if (parts.length) return parts.join("；");
    }
  }
  return fallback;
}