error.middleware.ts does not work properly without next parameter

[sfernengel]

Currently, the error middleware has the following code:

import { ErrorRequestHandler, Request, Response } from 'express';
import CustomError from '../errors/custom.error';

export const errorMiddleware: ErrorRequestHandler = (
  error: Error,
  _: Request,
  res: Response
) => 

When I run the code with an error, the error middleware does not get called. The signature must conform to what they expect. To make it runnable I suggest the following changes:

```typescript
import { ErrorRequestHandler, NextFunction, Request, Response } from 'express';
import CustomError from '../errors/custom.error';

export const errorMiddleware: ErrorRequestHandler = (
  error: Error,
  _: Request,
  res: Response,
  next: NextFunction
) => {