Fix custom APIs types

[infomiho]

I was building a custom API endpoint:

import { GetStaticResource } from "wasp/server/api";

export const getStaticResource: GetStaticResource = async (
  req,
  res,
  context
) => {
  return res.json({ message: "Hello from getStaticResource" });
};

When I type res. I don't get any autocomplete. When I clicked through the types of Api I found this:

It complains we are missing @types/express.

And when I changed express to express-serve-static-core, the types auto-complete worked.

Proposed implementation

We should either swap out express for express-serve-static-core when we are after Express types or investigate if there is a better way (a newer way) to get the Express types since Express development started again. (Maybe the solution will be upgrading to Express v5 in the end?)