/** tRPC 错误 → 用户可读文案：提取 zod 数组消息、兜底 HTML/网络异常。 */
export function formatTrpcError(err: unknown, fallback: string): string {
    const raw = err instanceof Error ? err.message : typeof err === "string" ? err : "";
    if (!raw) return fallback;
    if (raw.startsWith("<") || raw.includes("<!DOCTYPE")) {
        return "服务暂时不可用，请稍后重试";
    }
    try {
        const parsed: unknown = JSON.parse(raw);
        if (Array.isArray(parsed)) {
            const msgs = parsed
                .map((e) =>
                    e && typeof e === "object" ? (e as { message?: unknown }).message : null,
                )
                .filter((m): m is string => typeof m === "string" && m.length > 0);
            if (msgs.length > 0) return msgs.join("；");
        }
        if (parsed && typeof parsed === "object" && "message" in parsed) {
            const m = (parsed as { message?: unknown }).message;
            if (typeof m === "string" && m) return m;
        }
    } catch {
        /* 非 JSON，按原文处理 */
    }
    return raw;
}