TypeError: Cannot read properties of undefined (reading 'port')

[Wai Lee]

bogon:deno-react didi$ deno task dev
Task dev deno run -A dev.ts
Initialized aleph-compiler WebAssembly in 113.03ms.
INFO [dev] Watching for file changes...
error: Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'port')
port = (server.addrs[0] as Deno.NetAddr).port;
^
at serve (https://deno.land/std@0.155.0/http/server.ts:591:44)
at serve (https://deno.land/x/aleph@1.0.0-beta.21/server/mod.ts:407:5)
at serve (https://deno.land/x/aleph@1.0.0-beta.21/runtime/react/server.ts:40:3)
at file:///Users/didi/Desktop/projects/deno-react/server.ts:3:1

[Wai Lee]

import { serve } from "aleph/server";

serve({
  port: 8000
});