Logic issue in 22th problem example

[bacher]

I found the logical issue in 22th problem

Middleware type don't consider promises as output.

If we add one more middleware after middleware with async function we see that req become Promise:

Solution: add Promise<> variant to return value:

use<NewTOutput extends TOutput>(
    middleware: Middleware<TOutput, NewTOutput | Promise<NewTOutput>>
  ): DynamicMiddleware<TInput, NewTOutput>  {
    this.middleware.push(middleware);
    ...

+ | Promise<NewTOutput> solves the problem