Express.js Route Handler Registration (typescript)

1function Get(param?: string): any {
2  param = param || '/';
3  return (target: any, propertyKey: string): TypedPropertyDescriptor<any> => {
4    const descriptor = Object.getOwnPropertyDescriptor(target, propertyKey);
5    const originalMethod = descriptor.value;
6    target._routes = target._routes || [];
7    
8    function asyncMiddleware (request: Request, response: Response, next: NextFunction) {
9      const prom = originalMethod(request, response, next)
10      if (prom && prom.then) {
11        prom.then((result: any) => response.status(200).send(result)).catch((err: Error) => next(err))
12      }
13    }
14    target._routes.push({url: param, method: 'get',  handler: asyncMiddleware});
15    return descriptor;
16  };
17}