fix: support new vercel style

api/services/slack/[query].ts

@@ -0,0 +1,27 @@
+import {send, sendError, fetch} from '../../../util/http';
+import {NowRequest, NowResponse} from '@vercel/node';
+
+export default async function handler(
+  req: NowRequest,
+  res: NowResponse,
+): Promise<void> {
+  const {query} = req.query;
+
+  if (!query || typeof query !== 'string') {
+    return sendError(res, new Error('No query given'));
+  }
+
+  if (/[^a-zA-Z0-9_-]/.test(query)) {
+    return sendError(res, new Error('Invalid characters'));
+  }
+
+  try {
+    const response = await fetch(
+      `https://${encodeURIComponent(query)}.slack.com`,
+    );
+    const availability = response.status !== 200;
+    send(res, {availability});
+  } catch (err) {
+    sendError(res, err);
+  }
+}