Errors

if (error.code === "instance_limit_reached") {
  if (error.details.limit_source === "plan") {
    showUpgradePrompt(error.details.plan, error.details.instance_limit);
  } else {
    showContactProviderPrompt(error.details.instance_limit);
  }
}

async function send(body) {
  for (let attempt = 0; attempt < 5; attempt++) {
    const res = await fetch("https://api.bulkneo.com/v1/messages/text", {
      method: "POST",
      headers: {
        apikey: process.env.BULKNEO_API_KEY,
        "Content-Type": "application/json",
      },
      body: JSON.stringify(body),
    });

    if (res.status === 429) {
      const wait = Number(res.headers.get("retry-after") || 5);
      await new Promise((r) => setTimeout(r, wait * 1000));
      continue;
    }

    // Pace BEFORE you hit the wall: when the budget is spent, X-RateLimit-Reset
    // says how long until it is not. This scope is 'messages'; the instance
    // endpoints report their own, much larger budget under 'instances'.
    if (res.headers.get("x-ratelimit-remaining") === "0") {
      const wait = Number(res.headers.get("x-ratelimit-reset") || 1);
      await new Promise((r) => setTimeout(r, wait * 1000));
    }

    const json = await res.json();
    if (!res.ok) {
      // 409 and 4xx validation errors are not worth retrying.
      throw new Error(`${json.error.code}: ${json.error.message}`);
    }
    return json.data;
  }
  throw new Error("rate limited too many times");
}