use express types instead of custom versions

api/src/controllers/graphql.ts

@@ -1,12 +1,13 @@
-import { Request, Router, Response, NextFunction } from 'express';
+import { Router, Response } from 'express';
 import { graphqlHTTP } from 'express-graphql';
 import { GraphQLService } from '../services';
 import { respond } from '../middleware/respond';
+import asyncHandler from '../utils/async-handler';
 
 const router = Router();
 
 router.use(
-	asyncHandler(async (req: Request, res: Response, next: NextFunction) => {
+	asyncHandler(async (req, res, next) => {
 		const service = new GraphQLService({
 			accountability: req.accountability,
 			schema: req.schema,

api/src/utils/async-handler.ts

@@ -1,32 +1,19 @@
-import { NextFunction, Request, Response } from 'express';
-
-export type AsyncHandler<T> = (req: Request, res: Response, ...others: any) => Promise<T>;
-export type AsyncHandlerNext<T> = (req: Request, res: Response, next: NextFunction, ...others: any) => Promise<T>;
-export type AsyncHandlerError<T> = (
-	err: Error,
-	req: Request,
-	res: Response,
-	next: NextFunction,
-	...others: any
-) => Promise<T>;
-export type AsyncMiddleware<T> = AsyncHandler<T> | AsyncHandlerNext<T> | AsyncHandlerError<T>;
+import { RequestHandler, ErrorRequestHandler } from 'express';
 
 /**
  * Handles promises in routes.
  */
-function asyncHandler<T>(handler: AsyncMiddleware<T>): any {
-	if (handler.length == 2) {
-		return function (req: Request, res: Response, next: NextFunction, ...others: any) {
-			return Promise.resolve((handler as AsyncHandler<T>)(req, res, ...others)).catch(next);
-		};
-	} else if (handler.length == 3) {
-		return function (req: Request, res: Response, next: NextFunction, ...others: any) {
-			return Promise.resolve((handler as AsyncHandlerNext<T>)(req, res, next, ...others)).catch(next);
-		};
-	} else if (handler.length == 4) {
-		return function (err: Error, req: Request, res: Response, next: NextFunction, ...others: any) {
-			return Promise.resolve((handler as AsyncHandlerError<T>)(err, req, res, next, ...others)).catch(next);
-		};
+function asyncHandler(handler: RequestHandler): RequestHandler;
+function asyncHandler(handler: ErrorRequestHandler): ErrorRequestHandler;
+function asyncHandler(handler: RequestHandler | ErrorRequestHandler): RequestHandler | ErrorRequestHandler {
+	if (handler.length === 2 || handler.length === 3) {
+		const scoped: RequestHandler = (req, res, next) =>
+			Promise.resolve((handler as RequestHandler)(req, res, next)).catch(next);
+		return scoped;
+	} else if (handler.length === 4) {
+		const scoped: ErrorRequestHandler = (err, req, res, next) =>
+			Promise.resolve((handler as ErrorRequestHandler)(err, req, res, next)).catch(next);
+		return scoped;
 	} else {
 		throw new Error(`Failed to asyncHandle() function "${handler.name}"`);
 	}