Top level middleware for catching and displaying errors (assumes using error classes from @salsita/errors).
Expects logging function as parameter.
Example:
const winston = require("winston");
const Router = require("koa-router");
const errorMiddleware = require("@salsita/koa-error-middleware");
const formatUserMessage = err =>
process.env.NODE_ENV === "production" ? "Ooops something went wrong" : err.message;
const router = new Router();
router.use(errorMiddleware(winston.log, formatUserMessage));