[http-server-js][Bug]: adding a global policy throws an error

[benjlevesque]

Describe the bug

When using http-server-js with a custom global policy, an error is thrown.

const policy: Policy = async (ctx, next) => {
  next();
}
const router = createDemoServiceRouter({...}, { policies: [policy] });
// ...

this will always throw TypeError: Cannot read properties of undefined (reading 'catch')

Reproduction

Here is a repo with the reproduction of each case https://github.com/benjlevesque/repro-typespec-issues/blob/main/policy.test.ts

Resolution lead

The bug seems to be in the implementation of createPolicyChain, which does not return a Promise when at least one Policy is specified.
Adding async or returning Promise.resolve fixes the problem