Setup eslint and enforce rules

src/http/response/HTMLResponseFactory.ts

@@ -1,5 +1,5 @@
-import {ResponseFactory} from "./ResponseFactory";
-import {Request} from "../lifecycle/Request";
+import {ResponseFactory} from './ResponseFactory'
+import {Request} from '../lifecycle/Request'
 
 /**
  * Helper function that creates a new HTMLResponseFactory.
@@ -15,9 +15,11 @@ export function html(value: string): HTMLResponseFactory {
 export class HTMLResponseFactory extends ResponseFactory {
     constructor(
         public readonly value: string,
-    ) { super() }
+    ) {
+        super()
+    }
 
-    public async write(request: Request) {
+    public async write(request: Request): Promise<Request> {
         request = await super.write(request)
         request.response.setHeader('Content-Type', 'text/html; charset=utf-8')
         request.response.body = this.value