Near the top under the previous use statements you need to add

use App\Middleware\httpOptionsMiddleware;

This fix is a work of pure genius.

To install:

mkdir src/Middleware

create a new file named src/Middleware/httpOptionsMiddleware.php and put the contents of the above into it

Open src/Application.php and append the new hook for the middleware

// Add routing middleware.
->add(new RoutingMiddleware($this))

// add http options
->add( new HttpOptionsMiddleware($this))